Rhizobium meliloti lacking mosA synthesizes the rhizopine scyllo-inosamine in place of 3-O-methyl-scyllo-inosamine

Jp, Rao; Grzemski, Wojciech; Pj, Murphy

doi:10.1099/13500872-141-7-1683

Cited by 16 publications

(14 citation statements)

References 9 publications

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“…Our sequence analysis suggests that MOSA is closely related to DHDPS. Rao et al (1995) have shown that R. melitoti strains that lack the mosA gene produce the rhizopine scyllo-inosamine, whereas those that contain the mosA gene produce the rhizopine 3-o-methyl-scyllo-inosoa-mine. On this basis they argue that the probable role of MOSA is the methylation of scyllo-inosamine rather than the condensation of pyruvate to inositol (Murphy et al, 1993 (Kuhm et al, 1993).…”

Section: P¯anking Motif Is Taken By Janec ïEk As Possible Evidencmentioning

confidence: 98%

See 1 more Smart Citation

Structure and mechanism of a sub-family of enzymes related to N -acetylneuraminate lyase 1 1Edited by F. E. Cohen

Lawrence¹,

Barbosa²,

Smith³

et al. 1997

Journal of Molecular Biology

100

107

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Section: P¯anking Motif Is Taken By Janec ïEk As Possible Evidencmentioning

confidence: 98%

“…The reactions catalysed by these enzymes are summarised in Figure 1. A ®fth and tentative member of the family is the MosA protein (MOSA; Murphy et al, 1993;Rao et al, 1995), which is thought to Figure (Eaton & Chapman, 1992;Jeffcoat et al 1969b …”

Section: ; (3) Trans-o-hydroxybenzylidenepyruvatementioning

confidence: 99%

Structure and mechanism of a sub-family of enzymes related to N -acetylneuraminate lyase 1 1Edited by F. E. Cohen

Lawrence¹,

Barbosa²,

Smith³

et al. 1997

Journal of Molecular Biology

100

107

View full text Add to dashboard Cite

“…One superfamily member, the mosA gene product (Rhizobium meliloti), functions in rhizopine biosynthesis, a biosynthetic pathway that has not been fully characterized (11). Whereas studies of a mosA Ϫ mutant suggest that the MosA protein catalyzes methylation of a hydroxyl group (12), this predicted function is unexpected since it cannot be readily associated with a mechanism involving a protonated Schiff base functioning as an electron sink, e.g. the use of ␣-ketobutyrate as a methyl group donor is unprecedented in enzymology.…”

Section: The Enolase Superfamily: Abstraction Of the ␣-Protons Of Carmentioning

confidence: 99%

Understanding Enzyme Superfamilies

Babbitt

Gerlt

1997

Journal of Biological Chemistry

256

130

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Prior to the discovery in 1990 that mandelate racemase (MR) 1 and muconate-lactonizing enzyme (MLE) are structurally similar enzymes that catalyze different overall reactions (1), structurally related enzymes were assumed to catalyze identical chemical reactions but, perhaps, with distinct substrate specificities. For example, all of the members of the serine protease superfamily were known to catalyze the same chemistry, hydrolyses of peptide bonds, although their peptide substrates varied. As described by Craik and Perona in the previous minireview (2), evolutionary accommodation of these differences in substrate specificity can result in major reorganization of the associated structures.In this minireview, we discuss four recently discovered enzyme superfamilies in which an alternate theme predominates; within each of these superfamilies, the member proteins share a common structural scaffold but catalyze different overall reactions. For each of the superfamilies described, the active sites are contained within a single homologous domain. Although they represent several distinct family folds, the enzyme functions in each superfamily are related to their respective structural scaffolds in the same way; the proteins within each superfamily utilize a common mechanistic strategy for lowering the free energies of the rate-limiting transition states in the reactions they catalyze. The existence of several examples of such superfamilies lends further credence to the principle that the evolution of new catalytic activities involves the incorporation of new catalytic groups within an active site while retaining those groups necessary to catalyze the partial reaction common to all of them (3-5). As a consequence, the range of catalytic functions that can be accommodated by a single structural scaffold is considerably broader than had been previously suspected. Further, the diversity of function that each superfamily represents allows an economy in the number of unique protein folds required to support life and, as a result, undoubtedly has "simplified" the course of metabolic evolution. The Enolase Superfamily: Abstraction of the ␣-Protons of Carboxylic AcidsWe recently described the enolase superfamily, the members of which catalyze at least 11 different chemical reactions, including racemization, epimerization, and both syn and anti ␤-elimination reactions involving water, ammonia, or an intramolecular carboxylate group as leaving group (5).Despite broad differences in substrate structures and the overall reactions they catalyze, all of the reactions of the enolase superfamily are initiated by a common partial reaction, metal-assisted, general base-catalyzed abstraction of the ␣-proton of a carboxylate anion to generate a stabilized enolate anion intermediate (Reaction 1). However, the fate of the intermediate (protonation in the case of racemization and epimerization reactions and vinylogous ␤-elimination in the others) must be determined by the different functional groups that "surround" the intermediate in the a...

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“…Intriguingly, this region contains duplications of parts of the s 54 gene rpoN, a gene required for pnifH activity. Another copy of pnifH has been identified upstream of the mos operon in S. meliloti strains L5-30 (Murphy et al, 1988) and Rm220-3 (Rao et al, 1995). mos genes are involved in rhizopine production in these strains, but are absent from strain Rm1021.…”

Section: Promoter Duplication and Genome Adaptationmentioning

confidence: 99%

FixJ-regulated genes evolved through promoter duplication in Sinorhizobium meliloti

et al. 2004

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The FixLJ two-component system of Sinorhizobium meliloti is a global regulator, turning on nitrogen-fixation genes in microaerobiosis. Up to now, nifA and fixK were the only genes known to be directly regulated by FixJ. We used a genomic SELEX approach in order to isolate new FixJ targets in the genome. This led to the identification of 22 FixJ binding sites, including the known sites in the fixK1 and fixK2 promoters. FixJ binding sites are unevenly distributed among the three replicons constituting the S. meliloti genome: a majority are carried either by pSymA or by a short chromosomal region of non-chromosomal origin. Thus FixJ binding sites appear to be preferentially associated with the pSymA replicon, which carries the fixJ gene. Functional analysis of FixJ targets led to the discovery of two new FixJ-regulated genes, smc03253 and proB2. This FixJ-dependent regulation appears to be mediated by a duplication of the whole fixK promoter region, including the beginning of the fixK gene. Similar duplications were previously reported for the nifH promoter. By systematic comparison of all promoter regions we found 17 such duplications throughout the genome, indicating that promoter duplication is a common mechanism for the evolution of regulatory pathways in S. meliloti.

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Rhizobium meliloti lacking mosA synthesizes the rhizopine scyllo-inosamine in place of 3-O-methyl-scyllo-inosamine

Cited by 16 publications

References 9 publications

Structure and mechanism of a sub-family of enzymes related to N -acetylneuraminate lyase 1 1Edited by F. E. Cohen

Structure and mechanism of a sub-family of enzymes related to N -acetylneuraminate lyase 1 1Edited by F. E. Cohen

Understanding Enzyme Superfamilies

FixJ-regulated genes evolved through promoter duplication in Sinorhizobium meliloti

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