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129 巻, 4 号
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Tatsuo Nakayama, Yasunari Takami2001 年 129 巻 4 号 p. 491-499
発行日: 2001年
公開日: 2008/11/18
ジャーナル フリーAlterations in the chromatin structure are preferentially involved in the regulation of cell functions, including gene expression, in eukaryotes. Three types of mechanisms, by which the alterations are caused have been reported: (i) variants of histone subtypes, (ii) chromatin remodeling, and (iii) post-translational modification. This review focuses mainly on the first and third mechanisms, especially on the acetylation of core histones, one of the third mechanisms. Using the gene targeting technique for the DT40 chicken B cell line, we systematically generated a number of mutants, respectively, devoid of particular genes encoding histones and histone deacetylase(s) (HDACs). Most of the H1 and core histone variants should be involved positively or negatively in the transcription regulation of particular genes. Of the chicken HDACs (chHDACs), chHDAC-2 controls the amount of the IgM H-chain at the steps of both transcription and alternative premRNA processing, and chHDAC-3 is essential for cell viability, whereas chHDAC-1 merely affects gene expression in DT40 cells. These results indicate that HDAC family members should participate, in combination with one another, and/or histone acetyltransferase(s) (HATs), in the acetylation of core histones that regulates gene expression through alterations in the chromatin structure.抄録全体を表示PDF形式でダウンロード (1233K) -
Takemi Enomoto2001 年 129 巻 4 号 p. 501-507
発行日: 2001年
公開日: 2008/11/18
ジャーナル フリーEscherichia coli RecQ helicase is a component of the RecF pathway of recombination whose components are required to reassemble a replisome complex at the site of the replication fork after the removal of a lesion. There are at least five RecQ homologues in human cells, including BLM and WRN. The genes encoding BLM and WRN are mutated in the cancer-prone disorder Bloom's syndrome (BS) and the plogeroid disorder Werner's syndrome (WS), respectively. These syndromes are characterized by a high degree of genomic instability, including chromosomal breaks, multiple large deletions, and translocations, and cells derived from BS and WS patients show defects in DNA replication. Recently, it has become clear that a Holiday junction-like structure is formed at stalled replication forks to result in the formation of double-stranded breaks, and recombination plays an important role in the repair of stalled or broken replication forks, leading to the reinitiation of replication. Defects in the processing of stalled replication forks could lead to aberrant recombination events resulting in genetic instability. Recent studies on BLM, WRN, and the RecQ homologue of Saccharomyces crevisiae, Sgs1, indicate that these RecQ homologues interact with proteins involved in DNA replication, and function in a pathway from the DNA replication check point to homologous recombination.抄録全体を表示PDF形式でダウンロード (661K) -
Kimiko Hagino-Yamagishi, Masato Matsuoka, Masumi Ichikawa, Yoshihiro W ...2001 年 129 巻 4 号 p. 509-512
発行日: 2001年
公開日: 2008/11/18
ジャーナル フリーTo detect the biological activity of mammalian putative pheromone receptors (V1Rs and V2Rs), the mouse V1R gene was introduced into a primary culture of vomeronasal cells using the adenovirus expression system, and the response of these cells to mouse urine was analyzed by calcium imaging. These cells specifically responded to male but not female mouse urine. This response was attenuated by pertussis toxin, a specific inhibitor of G-protein Giα/Goα coupling from receptors. Our findings indicate that a putative pheromone receptor was specifically activated by mouse urine, a major source of mouse pheromones, and suggest that Gi/Go are functionally coupled with the receptor.抄録全体を表示PDF形式でダウンロード (988K) -
Chang-Hoon Han, Yukio Nisimoto, Sung-Haeng Lee, Eugene T. Kim, J. Davi ...2001 年 129 巻 4 号 p. 513-520
発行日: 2001年
公開日: 2008/11/18
ジャーナル フリーA series of truncated forms of gp91phox were expressed in Eseherichia coli in which the N-terminal hydrophobic transmembrane region was replaced with a portion of the highly soluble bacterial protein thioredoxin. TRX-gp9phox (306-569), which contains the putative FAD and NADPH binding sites, showed weak NADPH-dependent NBT (nitrobiue tetrazolium) reductase activity, whereas TRX-gp91phox (304-123) and THX-gp91phox (424-569) were inactive. Activity saturated at about a 1:1 molar ratio of FAD to TRX-gp91phox (306-569), and showed the same Km for NADPH as that for superoxide generating activity by the intact enzyme. Activity was not inhibited by superoxide dismutase, indicating that it was not mediated by superoxide, but was blocked by an inhibitor of the respiratory burst oxidase, diphenylene iodonium. In the presence of Rac1, the cytosolic regulatory protein p67phox stimulated the NBT reductase activity, but p47phox had no effect. Truncated p67phox containing the activation domain (residues 199-210) [C. -H. Han, J. R. Freeman, T. Lee, S. A. Motalebi, and J. D. Lambeth (1998) J. Biol. Chem. 273, 16663-16668] stimulated activity approximately 2-fold, whereas forms mutated or lacking this region failed to stimulate the activity. Our data indicate that: (i) TRX-gp91phox (306-569) contains binding sites for both pyridine and flavin nucleotides; (ii) this flavoprotein domain shows weak diaphorase activity; and (iii) the flavin-binding domain of gp91phox is the target of regulation by the activation domain of p67phox.抄録全体を表示PDF形式でダウンロード (1491K) -
Toshiyuki Yamaji, Sachiko Nakamura, Hiromu Takematsu, Toshiyuke Kawasa ...2001 年 129 巻 4 号 p. 521-527
発行日: 2001年
公開日: 2008/11/18
ジャーナル フリーIn our previous study, the sphingosine-like immunosuppressant ISP-1 was shown to induce apoptosis in the mouse cytotoxic T cell line CTLL-2. In this study, we characterized the ISP-1-induced apoptotic pathway. Although caspase-3-like protease activity increases concomitantly with ISP-1-induced apoptosis in CTLL-2 cells, the apoptosis is not inhibited by caspase-3-like protease inhibitors, i.e. DEVD-cho and z-DEVD-fmk. In contrast, sphingosine-induced apoptosis in CTLL-2 cells is caspase-3-like protease-dependent. A caspase inhibitor with broad specificity, z-VAD-fmk, protects cells from apoptosis induced by ISP-1, indicating that ISP-1-induced apoptosis is dependent on caspase (s) other than caspase-3. Overexpression of Bcl-2 or Bcl-xL suppresses the apoptosis induced by ISP-1, although sphingosine-induced apoptosis is not efficiently inhibited by Bcl-2. Finally, ISP-1-induced mitochondrial depolarization, which is thought to be a checkpoint dividing the apoptotic pathway into upstream and downstream stages, is not inhibited by DEVD-cho, but is inhibited by z-VAD-fmk. These data suggest that a pathway dependent on caspase(s) other than caspase-3 is involved upstream of mitochondrial depolarization in ISP-1-induced apoptosis.抄録全体を表示PDF形式でダウンロード (594K) -
Saori Takahashi, Keitaro Takahashi, Takahiro Kaneko, Hironobu Ogasawar ...2001 年 129 巻 4 号 p. 529-535
発行日: 2001年
公開日: 2008/11/18
ジャーナル フリーRenin-binding protein (RnBP) is an endogenous renin inhibitor originally isolated from porcine kidney. It was recently identified as the enzyme N-acetyl-D-glucosamine (G1cNAc) 2-epimerase [Takahashi, S. et al. (1999) J. Biochem. 125, 348-353] and its active site residue was determined to be cysteine 380 by site-directed mutagenesis [Takahasbi, S. et al. (1999) J. Biochem. 126, 639-642]. To further investigate the relationship between structure and function of recombinant human (rh) RnBP as a G1cNAc 2-epimerase, we have constructed several C-terminal deletion and multi-cysteine/serine mutants of rhGlcNAc 2-epimerase and expressed them in Escherichia coli cells. The expression was detected by Western blotting using anti-rhRnBP antiserum. The C-terminal deletion mutant, Δ400-417, had approximately 50% activity relative to the wild-type enzyme, but other C-terminal deletion mutants, Δ380-417, Δ386-417, and Δ390-417, had no enzymatic activity. Mutational analysis of mufti-cysteine/serine mutants revealed that cysteines 41 and 390 were critical for the activity or stabilization of the enzyme, while cysteine residues in the middle of the enzyme, cysteines 125, 210, 239, and 302, had no essential function in relation to the activity.抄録全体を表示PDF形式でダウンロード (1032K) -
Yosuke Otake, Ichiro Fujimoto, Fumihiro Tanaka, Tatsuo Nakagawa, Takes ...2001 年 129 巻 4 号 p. 537-542
発行日: 2001年
公開日: 2008/11/18
ジャーナル フリーThe structures of N-linked oligosaccharides present in human sera from 12 healthy volunteers and from 14 patients with non-small cell lung cancer (NSCLC) were analyzed by our recently developed partially automated systematic method. Thirty different structures of oligosaccharides were deduced, and these accounted for 84.1% of the total N-linked oligosaccharides present in human sera. All of the quantified oligosaccharide levels in healthy human sera were within twice the standard deviation. The amount of a triantennary trigalactosylated structure with one outer arm fucosylation (A3G3Fo) was found to be markedly increased in NSCLC patients in comparison to that in healthy volunteers (p<0.01). No significant positive correlation with other clinical data was found. Serum A3G3Fo levels can thus be a novel marker for the diagnosis of NSCLC.抄録全体を表示PDF形式でダウンロード (1330K) -
Paul J. Thornalley, Ismat Jahan, Rita Ng2001 年 129 巻 4 号 p. 543-549
発行日: 2001年
公開日: 2008/11/18
ジャーナル フリーThe accumulation of triosephosphates and the increased formation of the potent glycating agent methylglyoxal in intracellular hyperglycaemia are implicated in the development of diabetic complications. A strategy to counter this is to stimulate the anaerobic pentosephosphate pathway of glycolysis by maximizing transketolase activity by thiamine supplementation, with the consequent consumption of glyceraldehyde-3-phosphate and increased formation of ribose-5-phosphate. To assess the effect of thiamine supplementation on the accumulation of triosephosphates and methylglyoxal formation in cellular hyperglycaemia, we incubated human red blood cell suspensions (50% v/v) in short-term culture with 5mM glucose and 50mM glucose in Krebs-Ringer phosphate buffer at 37°C as models of cellular metabolism under normoglycaemic and hyperglycaemic conditions. In hyperglycaemia, there is a characteristic increase in the concentration of the triosephosphate pool of glycolytic intermediates and a consequent increase in the concentration and metabolic flux of the formation of methylglyoxal. The addition of thiamine (50-500μM) increased the activity of transketolase, decreased the concentration of the triosephosphate pool, decreased the concentration and metabolic flux of the formation of methylglyoxal, and increased the concentration of total sedoheptulose-7-phosphate and ribose-5-phosphate. Biochemical changes implicated in the development of diabetic complications were thereby prevented. This provides a biochemical basis for high dose thiamine therapy for the prevention of diabetic complications.抄録全体を表示PDF形式でダウンロード (621K) -
Ilse Stevens, Evelien Rondelez, Wilfried Merlevede, Jozef Goris2001 年 129 巻 4 号 p. 551-560
発行日: 2001年
公開日: 2008/11/18
ジャーナル フリーThe different oligomers composing the high molecular weight calcium/calmodulin-dependent protein kinase II (CaMKII) holoenzyme, previously shown to be transiently activated during Xenopus oocyte maturation, migrate on SDS-PAGE as proteins of 83, 72, 62, 56, and 52 kDa and have all been cloned. The holoenzyme consists of the CaMKII isoforms γB, γC, and δ12, already described in other species, while γJ, γK, γL, γM, and γN are now described for the first time. The γ-isoforms are splice variants of the γ-gene, containing in their variable region different combinations of known exons and one, two or three novel exons. Semi-quantitative RT-PCR revealed that all isoforms identified in prophase oocytes are also expressed in adult tissues with a tissue-specific expression pattern. At least thirty different CaMKII isoforms could be identified in different Xenopus adult tissues, most of which are described here for the first time.抄録全体を表示PDF形式でダウンロード (2886K) -
Masatomo Kaji, Masaomi Ikari, Shuhei Hashiguchi, Yuji Ito, Ryo Matsumo ...2001 年 129 巻 4 号 p. 577-583
発行日: 2001年
公開日: 2008/11/18
ジャーナル フリーIn this study, we attempted to analyze the peptide motifs recognized by 24822.111 and F9, monoclonal antibodies (mAbs) that inhibit the chemotactic activity of monocyte chemoattractant protein-1 (MCP-1), a member of the CC subfamily of chemokines. We isolated phage clones from a phage display library and identified six peptide motifs. One of these clones, C27, was strongly and specifically recognized by 24822.111 mAb, while another, G25, was similarly recognized by F9 mAb. Both the C27 motif and the G25 motif contain two cysteines in their sequences and have little homology to the primary amino acid sequence of MCP-1. These clones, however, bound to THP-1 cells, and the binding was competitively inhibited by MCP-1. The clones strongly inhibited the MCP-1-induced chemotaxis of human monocytes. The synthetic and intramolecularly disulfide-linked peptides of C27 and G25 (sC27 and sG25) also inhibited the chemotaxis induced by MCP-1, while their derivatives with serine in place of cysteine did not, suggesting the importance of the loop structure for the inhibition. These results suggest that sC27 and sG25 may mimic the MCP-1-binding domain to the MCP-1 receptor.抄録全体を表示PDF形式でダウンロード (1068K) -
Koichi Katsuyama, Yukio Hirata2001 年 129 巻 4 号 p. 585-591
発行日: 2001年
公開日: 2008/11/18
ジャーナル フリーWe previously showed that 1-[3-(3-pyridyl)-acryloyl]-2-pyrrolidinone hydrochloride (N2733) inhibits lipopolysaccharide (LPS)-induced tumour necrosis factor (TNF)-α secretion and improves the survival of endotoxemic mice. Since overproduction of nitric oxide (NO) by inducible NO synthase (iNOS) in vascular smooth muscle cells (VSMCs) is largely responsible for the development of endotoxemic shock, and iNOS gene expres-sion is mainly regulated by LPS and inflammatory cytokines, we studied whether or not N2733 affects interleukin (IL)-1β-induced iNOS gene expression, NF-KB activation, and NF-KB inhibitor (IKB)-α degradation in cultured rat VSMCs. N2733 dose-dependently (10-100μM) inhibited IL-1β-stimulated NO production, and decreased IL-1β-induced iNOS mRNA and protein expression, as found on Northern and Western blot analyses, respectively. Gel shift assay and an immunocytochemical study showed that N2733 inhibited IL-1β-induced NF-KB activation and its nuclear translocation. Western blot analyses involving anti-IKB-α and anti-phospho IKB-α antibodies showed that IL-1β induced transient degradation of IKB-α preceded by the rapid appearance of phosphorylated IKB-α, both of which were markedly blocked by N2733. N2733 blocked IL-1β-induced phosphorylated IKB-α even in the presence of a proteasome inhibitor (MG115). hmnunoblot analysis involving anti-IKB kinase (IKK)-α and anti-phosphoserine antibodies revealed that N2733 inhibited IL-1β-induced IKK-α phosphorylation, whereas N2733 had no inhibitory effect on IL-1β-stimulated p42/p44 MAP kinase or p3S MAP kinase activity. Our results suggest that the inhibitory action of N2733 toward IL-1β-induced NF-KB activation and iNOS expression is due to its blockade of the upstream signal(s) leading to IKK-α activation, and subsequent phosphorylation and degradation of IKB-α in rat VSMCs.抄録全体を表示PDF形式でダウンロード (2706K) -
Ryuta Kanai, Keiko Haga, Kunio Yamane, Kazuaki Harata2001 年 129 巻 4 号 p. 593-598
発行日: 2001年
公開日: 2008/11/18
ジャーナル フリー1-Deoxynojirimycin, a pseudo-monosaccharide, is a strong inhibitor of glucoamylase but a relatively weak inhibitor of cyclodextrin glucanotransferase (CGTase). To elucidate this difference, the crystal structure of the CGTase from alkalophilic Bacillus sp. 1011 complexed with 1-deoxynojirimycin was determined at 2.0 Å resolution with the crystallographic R value of 0.154 (Rfree=0.214). The asymmetric unit of the crystal contains two CGTase molecules and each molecule binds two 1-deoxynojirimycin. One 1-deoxynojirimycin molecule is bound to the active center by hydrogen bonds with catalytic residues and water molecules, but its binding mode differs from that expected in the substrate binding. Another 1-deoxynojirimycin found at the maltose-binding site 1 is bound to Asn-667 with a hydrogen bond and by stacking interaction with the indole moiety of Trp-662 of molecule 1 or Trp-616 of molecule 2. Comparison of this structure with that of the acarbose-CGTase complex suggested that the lack of stacking interaction with the aromatic side chain of Tyr-100 is responsible for the weak inhibition by 1-deoxynojirimycin of the enzymatic action of CGTase.抄録全体を表示PDF形式でダウンロード (2604K) -
Asahiko Takahashi, Hisako Muramatsu, Shin Takagi, Hajime Fujisawa, Yoz ...2001 年 129 巻 4 号 p. 599-606
発行日: 2001年
公開日: 2008/11/18
ジャーナル フリーPrp8 is a splicing factor of 220 kDa originally identified in yeast and is a component of the U5 small nuclear ribonucleoprotein particle. Mouse Prp8 cDNA was cloned and shown to share 62.6 and 68.2% sequence identity with the yeast homologue at the amino acid and nucleotide level, respectively, while it differs by only 3 amino acid residues from the human homologue. During mouse embryogenesis, Prp8 is expressed intensely at day 9.5 of gestation, and its expression decreases progressively during embryogenesis. In adult mice, Prp8 is expressed strongly in the testis and moderately in the ovary. In situ hybridization analysis revealed that Prp8 is preferentially expressed in the outer cell layer in the testis, probably in the spermatogonia and primary spermatocytes, and in granulosa cells in the ovary. In Caenorhabditis elegans, microinjection of a double stranded RNA corresponding to a portion of the Prp8 sequence results in the arrest of embryogenesis at the late-gastrulation stage. These results suggest that Prp8 plays an important role in reproduction and development. Prp8 was shown to bind to midkine (MK), a heparin-binding growth factor. Since Prp8 expression partially overlaps with the sites of action of MK, it is possible that binding to Prp8 is involved in part of MK signaling.抄録全体を表示PDF形式でダウンロード (3723K) -
Toshi Shimamoto, Tadashi Shimamoto, Xing-Jue Xu, Noriko Okazaki, Hidey ...2001 年 129 巻 4 号 p. 607-613
発行日: 2001年
公開日: 2008/11/18
ジャーナル フリーWild-type Citrobacter freundii cannot grow on melibiose as a sole source of carbon. The melibiose transporter gene melB was cloned froma C. freundii mutant M4 that could utilize melibiose as a sole carbon source- Although the cloned melB gene is closely siunilar to the melB genes of other bacteria, it is cryptic because of a frameshift mutation. Site-directed mutagenesis was used to construct a functional melB gene by deleting one nucleotide, resulting in the production of an active melibiose transporter. The active MelB transporter could utilize Na+ and H+ as coupling cation to melibiose transport. The amino acid sequence of the C. freundii MelB was found to be most similar to those of Salmonella typhimurium and Escherichia coli MelB. These facts are consistent with the phylogenetic relationship of bacteria and the cation coupling properties of the melibiose transporters.抄録全体を表示PDF形式でダウンロード (600K) -
Daiju Okuda, Chihiro Nozaki, Fujio Sekiya, Takashi Morita2001 年 129 巻 4 号 p. 615-620
発行日: 2001年
公開日: 2008/11/18
ジャーナル フリーSpecies in the genus Echis have been classified mainly based on their morphological appearance and the analytical patterns of their serum. However, re-classification of the genus Echis has recently been suggested by taxonomists, toxicologists, and clinicians, since there have been problems with the current classification, such as the efficacy of antivenoms used for treating bites and the broad geographical distribution of Echis snakes. In this study, we purified five novel disintegrins, the platelet aggregation inhibitors pyramidin A and B from the venom of Echis pyramidum, ocellatin from the venom of Echis ocellatus, and leucogastin A and B from the venom of Echis leucogaster, to compare their sequences and allow us to re-evaluate the classification of various species in the genus Echis. Comparison of the amino acid sequences of five new and four known isolated disintegrins from snake venoms of six Echis species and their distribution strongly support the recent re-classification of the genus Echis.抄録全体を表示PDF形式でダウンロード (1111K) -
Jesús M. Salvador, Manuel Berengena, M. Rosario Sepúlved ...2001 年 129 巻 4 号 p. 621-626
発行日: 2001年
公開日: 2008/11/18
ジャーナル フリーThe presence and distribution of sarco-endoplasmic reticulum Ca2+-ATPase (SERCA) isoform 2b in microsomes and other subcellular fractions isolated from pig brain has been demonstrated by the combined use of a specific antibody raised against the SERCA2b isoform and ATP phosphorylation experiments. All subcellular fractions show an approximately 110 kDa phosphorylated protein, the band intensity being stronger in microsomes. Preliminary treatment of the samples with trypsin generates two phosphorylated fragments of about 57 and 33 kDa in the presence of Ca2+. The observed fragments are typical trypsinized products of the SERCA2b isoform. The monoclonal antibody Y/1F4 raised against the sarcoplasmic reticulum Ca2+-ATPase (isoform 1) binds to the 110 kDa band in membranes isolated from brain. The binding was stronger in microsomes than in other fractions. Furthermore, this antibody also recognizes a clear band at around 115 kDa. This band is always stronger in plasma membrane than in synaptosomes or microsomes and is unaffected by trypsin. Phosphorylation studies in the absence of Ca2+ suggest that the 115 kDa protein is not a Ca2+-ATPase.抄録全体を表示PDF形式でダウンロード (2644K) -
Tetsuya Ishikawa, Hiroshi Terai, Takashi Kitajima2001 年 129 巻 4 号 p. 627-633
発行日: 2001年
公開日: 2008/11/18
ジャーナル フリーCollagen is generally incapable of capturing polypeptides such as growth factors in a specific manner. In this study, we established a collagen-binding growth factor (FNCBD-EGF) consisting of epidermal growth factor (EGF) and the fibronectin collagen-binding domain. A typical yield of FNCBD-EGF was approximately 200μg/ml culture in an Escherichia coli expression system. This fusion protein bound to gelatin and fibrillar collagen sponges, and the bound protein was not effectively eluted even with 2M NaCl. In addition, FNCBD-EGF bound to type I, II, III, or IV collagen-coated plates, and the specificity of binding was confirmed by competitive inhibition using fibronectin. FNCBD-EGF substantially stimulated cell growth after binding to collagen-coated culture plates, whereas EGF had no effect, indicating that this fusion protein acted as a collagen-associated growth factor. In an animal model of impaired wound healing, FNCBD-EGF, but not EGF, was retained with collagen sponges at wound sites 4d after implantation, and repair of epidermis was observed underneath the sponges. These results suggested that our fusion protein with high collagen affinity would be useful for wound healing.抄録全体を表示PDF形式でダウンロード (2142K) -
Falk Hlubek, Christian Löhberg, Johannes Meiler, Andreas Jung, Th ...2001 年 129 巻 4 号 p. 635-641
発行日: 2001年
公開日: 2008/11/18
ジャーナル フリーTip60 was originally identified as cellular HIV-Tat interacting protein and has been shown to augment Tat-dependent transcription. It has also been shown to interact with various cellular transcription factors and to belong to the nuclear histone acetyltransferase (HAT) family. To further elucidate the function of Tip60 and its HAT domain in transcription regulation, we compared Tip60 activity in HeLa and Jurkat T lymphoma cells. Here we show that Tip60 augments the HTV-1 Tat activity at the HIV-LTR promoter in HeLa but inhibits it in Jurkat cells. Moreover, we isolated two new variants of the Tip60 protein (Tip60Δ1, Tip60Δ2) from Jurkat cells. The Tip60Δ2 variant lacks the entire HAT domain but modulates HIV-1 Tat activity like full-length Tip60. In addition, Tip60 and the transcriptional repressor ZEB (zinc finger E box binding protein) interact specifically in the yeast two-hybrid system and additively inhibit the CD4 enhancer/promoter activity in Jurkat cells. Thus, Tip60 may function as corepressor of the ZEB protein. In summary, these data show that Tip60 functions as a cell-type-specific transcriptional regulator and that the HAT domain is not required for either transcriptional activation or inhibition. This indicates that Tip60 may function by recruiting additional cell-type-specific cofactors.抄録全体を表示PDF形式でダウンロード (1234K) -
Yasuyuki Nakamura, Ken-ichi Yoshioka, Hitoshi Shirakawa, Michiteru Yos ...2001 年 129 巻 4 号 p. 643-651
発行日: 2001年
公開日: 2008/11/18
ジャーナル フリーNonhistone protein HMG2, like HMG1, binds with B-DNA in a sequence-nonspecific manner and causes structural alterations in DNA such as bending, kinking and unwinding. Here, we studied the functions of HMG2 domains in the DNA structural alteration and modulation by using various HMG2 peptides, and we demonstrated several new findings. The HMG box itself as a DNA-binding motif may have the basic function of inducing curvature, resulting in the apparent DNA bending in the DNA cyclization assay, but not of abruptly kinking DNA. The DNA-binding activity of HMG box B, which is enhanced by the presence of box A, together with the flanking regions of box B, causes DNA bending accompanying the kinking of the DNA main chain. The DNA unwinding accompanied by DNA kinking diminishes cruciform structures in supercoiled DNA. Analysis using mutant peptides for box A confirmed that box A in HMG2 functions as a mediator of DNA structural alteration together with box B. The present studies on the functional properties of the respective regions of HMG2 may help to elucidate the protein function.抄録全体を表示PDF形式でダウンロード (3968K)
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