Abstract
The PII protein is a signal transducer that is concerned in archaea, bacteria, and plants. While the role of PII in the regulation of nitrogen assimilation has been established in the prokaryotes, its role in plants has not been elucidated. To study the role of plant PII using the moss Physcomitrella patens, which is amenable to gene manipulation through homologous recombination, we isolated a cDNA of the PII gene, PpGLB1, from a cDNA library. The deduced PpGLB1 protein is 232 amino acid long, including a putative chloroplast transit peptide. The predicted peptide sequence showed 48% identity (74% homology) with that of A. thaliana PII. PpGLB1 was shown to be a single copy gene by Southern blot analysis. RT-PCR analysis showed that PpGLB1 mRNA is constitutively expressed in the protonema under various nutritional and light conditions. The expression pattern of PpGLB1 was thus different from that of AtGLB1.
