This Article Full Text (PDF) Other Versions of this Article: JB.01707-06v1 189/9/3445    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Poysti, N. J. Articles by Oresnik, I. J. Search for Related Content PubMed PubMed Citation Articles by Poysti, N. J. Articles by Oresnik, I. J.

 Previous Article  |  Next Article 

J. Bacteriol. doi:10.1128/JB.01707-06
Copyright (c) 2007, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

Characterization of Sinorhizobium meliloti triose phosphate isomerase genes

University of Manitoba, Winnipeg, MB, Canada R3T 2N2

^* To whom correspondence should be addressed. Email: oresniki{at}cc.umanitoba.ca.

	Abstract

A Tn5 mutant strain of Sinorhizobium meliloti was isolated with an insertion in tpiA (Systematic identifier: SMc01023), a putative triose phosphate isomerase (TPI) encoding gene. The tpiA mutant grew slower than wild-type on rhamnose and did not grow with glycerol as a sole carbon source. The genome of S. meliloti wild-type Rm1021 contains a second predicted TPI encoding gene tpiB (SMc01614). We have constructed mutations and confirmed that both genes encode functional TPI enzymes. tpiA appears to be constitutively expressed and provides the primary TPI activity for central metabolism. tpiB has been shown to be required for growth with erythritol. TpiB activity is induced by growth with erythritol, however, basal levels of TpiB activity present in tpiA mutants allow for growth with gluconeogenic carbon sources. Although tpiA mutants can be complemented by tpiB, tpiA cannot substitute for mutations in tpiB with respect to erythritol catabolism. Mutations in tpiA or tpiB alone do not cause symbiotic defects, however, mutations in both tpiA and tpiB caused reduced symbiotic nitrogen fixation.