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Highly Conserved Genes In Geobacter Species With Expression Patterns Indicative Of Acetate Limitation, Derek Lovley, Carla Risso, Barbara A. Methé, Hila Elifantz, Dawn E. Holmes
Highly Conserved Genes In Geobacter Species With Expression Patterns Indicative Of Acetate Limitation, Derek Lovley, Carla Risso, Barbara A. Methé, Hila Elifantz, Dawn E. Holmes
Carla Risso
Analysis of the genome of Geobacter sulfurreducens revealed four genes encoding putative symporters with homology to ActP, an acetate transporter in Escherichia coli. Three of these genes, aplA, aplB and aplC, are highly similar (over 90 % identical) and fell within a tight phylogenetic cluster (Group I) consisting entirely of Geobacter homologues. Transcript levels for all three genes increased in response to acetate limitation. The fourth gene, aplD, is phylogenetically distinct (Group II) and its expression was not influenced by acetate availability. Deletion of any one of the three genes in Group I did not significantly affect acetate-dependent growth, suggesting …
Elucidation Of An Alternate Isoleucine Biosynthesis Pathway In Geobacter Sulfurreducens, Derek Lovley, Carla Risso, Stephen J. Van Dien, Amber Orloff, Maddalena V. Coppi
Elucidation Of An Alternate Isoleucine Biosynthesis Pathway In Geobacter Sulfurreducens, Derek Lovley, Carla Risso, Stephen J. Van Dien, Amber Orloff, Maddalena V. Coppi
Carla Risso
The central metabolic model for Geobacter sulfurreducens included a single pathway for the biosynthesis of isoleucine that was analogous to that of Escherichia coli, in which the isoleucine precursor 2-oxobutanoate is generated from threonine. 13C labeling studies performed in G. sulfurreducens indicated that this pathway accounted for a minor fraction of isoleucine biosynthesis and that the majority of isoleucine was instead derived from acetyl-coenzyme A and pyruvate, possibly via the citramalate pathway. Genes encoding citramalate synthase (GSU1798), which catalyzes the first dedicated step in the citramalate pathway, and threonine ammonia-lyase (GSU0486), which catalyzes the conversion of threonine to 2-oxobutanoate, were …