About one-third of all proteins are metalloproteins, which play fundamental roles in nature. In particular, FeS proteins are the most ubiquitous and represent diverse functions such as electron transfer, enzyme reaction and gene expression. Metal ions are precisely delivered to the target proteins by specific carrier proteins (metallochaperone). This review will describe the crystal structures of the oxidative stress sensor SoxR, and [NiFe] hydrogenase maturation proteins.
Interaction between the mammalian cell polarity proteins Inscuteable (mInsc) and LGN plays crucial roles in mitotic spindle orientation, a process contributing to asymmetric cell division. We describe here the crystal structure of the LGN-binding domain (LBD) of human mInsc in complex with the N-terminal TPR domain of human LGN at 2.6 Å resolution. mInsc-LBD adopts an elongated structure containing an α-helix and an antiparallel β-sheet linked by an extended region and runs antiparallel to LGN along the concave surface of the superhelix formed by the TPR motifs, indicative of a novel mode for TPR interaction. Characteristics of interaction between LGN TPR domain and other partner molecules are discussed.
The cytidine at the first position of the anticodon (C34) in the AUA codon-specific archaeal tRNAIle2 is modified to 2-agmatinylcytidine (agm2C), which is crucial for the precise decoding of the genetic code. This modification is catalyzed by tRNAIle-agm2C synthetase (TiaS), using ATP and agmatine as substrates. We have determined the crystal structures of TiaS-tRNAIle2 complexed with ATP, or with AMPcPP and agmatine, revealing a novel kinase module requisite for activating C34 by phosphorylation. These structures showed that agmatine is essential for placing C34 in the active site. We also revealed the molecular mechanism by which TiaS discriminates tRNAIle2 from other tRNAs.
Channelrhodopsin (ChR) is a light-gated cation channel derived from algae that conducts cations, including sodium ions, in a light-dependent manner. Because the inward flow of sodium ions triggers the neuron firing, neurons expressing ChRs can be optically controlled even within freely moving mammals. Although ChR has been broadly applied to neuroscience research, little is known about its molecular mechanisms. We determined the crystal structure of ChR at 2.3 Å resolution and revealed its molecular architecture, especially, the cation-conducting pathway. The integration of structural and electrophysiological analyses provided insight into the molecular basis for the remarkable function of ChR, and paved the way for the principled design of ChR variants with novel properties.
Ferroelectric material studies, e.g., ferroelectric phase transition of BaTiO3, and CdTiO3, those involving soft-mode phonon, ferroelectric structure and, its materials properties using state-of-the-art first-principles calculations are described.