The Escherichia coli signal transducers PII (GlnB) and GlnK form heteromers in vivo: fine tuning the nitrogen siganl cascade.

W.C. van Heeswijk, D. Wen, P. Clancy, H.V. Westerhoff, S.G. Vasudevan

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

The PII protein is Escherichia coli's cognate transducer of the nitrogen signal to the NRII (NtrB)/NRI (NtrC) two-component system and to adenylyltransferase. Through these two routes, PII regulates both amount and activity of glutamine synthetase. GInK is the recently discovered paralogue of PII, with a similar trimeric x-ray structure. Here we show that PII and GlnK form heterotrimers, in E. coli grown in nitrogen-poor medium. In vitro, fully uridylylated heterotrimers of the two proteins stimulated the deadenylylation activity of adenylyltransferase, albeit to a lower extent than homotrimeric PII-UMP. Fully uridylylated GlnK did not stimulate, or hardly stimulated, the deadenylylation activity. We propose that uridylylated Pll/GlnK heterotrimers fine-regulate the activation of glutamine synthetase. The Pll/GlnK couple is a first example of prokaryotic signal transducer that can form heterotrimers. Advantages of hetero-oligomer formation as molecular mechanism for fine-regulation of signal transduction are discussed.
Original languageEnglish
Pages (from-to)3942-3947
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume97
DOIs
Publication statusPublished - 2000

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