5dn1 | pdb_00005dn1
Crystal structure of Phosphoribosyl isomerase A from Streptomyces coelicolor
Structural highlights
FunctionHIS4_STRCO Catalyzes the isomerization of the aminoaldose moiety of ProFAR to the aminoketose of PRFAR in the biosynthesis pathway for histidine and the isomerization of the aminoaldose PRA to the aminoketose CdRP in the biosynthsis pathway for tryptophan.[HAMAP-Rule:MF_01014] Publication Abstract from PubMedWe investigate the evolution of co-occurring analogous enzymes involved in L-tryptophan and L-histidine biosynthesis in Actinobacteria Phylogenetic analysis of trpF homologues, a missing gene in certain clades of this lineage whose absence is complemented by a dual-substrate HisA homologue, termed PriA, found that they fall into three categories: (i) trpF-1, an L-tryptophan biosynthetic gene horizontally acquired by certain Corynebacterium species; (ii) trpF-2, a paralogue known to be involved in synthesizing a pyrrolopyrrole moiety and (iii) trpF-3, a variable non-conserved orthologue of trpF-1 We previously investigated the effect of trpF-1 upon the evolution of PriA substrate specificity, but nothing is known about the relationship between trpF-3 and priA After in vitro steady-state enzyme kinetics we found that trpF-3 encodes a phosphoribosyl anthranilate isomerase. However, mutation of this gene in Streptomyces sviceus did not lead to auxothrophy, as expected from the biosynthetic role of trpF-1 Biochemical characterization of a dozen co-occurring TrpF-2 or TrpF-3, with PriA homologues, explained the prototrophic phenotype, and unveiled an enzyme activity trade-off between TrpF and PriA. X-ray structural analysis suggests that the function of these PriA homologues is mediated by non-conserved mutations in the flexible L5 loop, which may be responsible for different substrate affinities. Thus, the PriA homologues that co-occur with TrpF-3 represent a novel enzyme family, termed PriB, which evolved in response to PRA isomerase activity. The characterization of co-occurring enzymes provides insights into the influence of functional redundancy on the evolution of enzyme function, which could be useful for enzyme functional annotation. Co-occurrence of analogous enzymes determines evolution of a novel (betaalpha)8-isomerase sub-family after non-conserved mutations in flexible loop.,Verduzco-Castro EA, Michalska K, Endres M, Juarez-Vazquez AL, Noda-Garcia L, Chang C, Henry CS, Babnigg G, Joachimiak A, Barona-Gomez F Biochem J. 2016 May 1;473(9):1141-52. doi: 10.1042/BJ20151271. Epub 2016 Feb 29. PMID:26929404[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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