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Crystal structures and mutational analyses of acyl-CoA carboxylase beta subunit of Streptomyces coelicolor.

ABSTRACT: The first committed step of fatty acid and polyketides biosynthesis, the biotin-dependent carboxylation of an acyl-CoA, is catalyzed by acyl-CoA carboxylases (ACCases) such as acetyl-CoA carboxylase (ACC) and propionyl-CoA carboxylase (PCC). ACC and PCC in Streptomyces coelicolor are homologue multisubunit complexes that can carboxylate different short chain acyl-CoAs. While ACC is able to carboxylate acetyl-, propionyl-, or butyryl-CoA with approximately the same specificity, PCC only recognizes propionyl- and butyryl-CoA as substrates. How ACC and PCC have such different specificities toward these substrates is only partially understood. To further understand the molecular basis of how the active site residues can modulate the substrate recognition, we mutated D422, N80, R456, and R457 of PccB, the catalytic beta subunit of PCC. The crystal structures of six PccB mutants and the wild type crystal structure were compared systematically to establish the sequence-structure-function relationship that correlates the observed substrate specificity toward acetyl-, propionyl-, and butyryl-CoA with active site geometry. The experimental data confirmed that D422 is a key determinant of substrate specificity, influencing not only the active site properties but further altering protein stability and causing long-range conformational changes. Mutations of N80, R456, and R457 lead to variations in the quaternary structure of the beta subunit and to a concomitant loss of enzyme activity, indicating the importance of these residues in maintaining the active protein conformation as well as a critical role in substrate binding.

SUBMITTER: Arabolaza A

PROVIDER: S-EPMC2927733 | biostudies-literature | 2010 Aug

REPOSITORIES: biostudies-literature

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Crystal structures and mutational analyses of acyl-CoA carboxylase beta subunit of Streptomyces coelicolor.

Arabolaza Ana A Shillito Mary Elizabeth ME Lin Ting-Wan TW Diacovich Lautaro L Melgar Melrose M Pham Huy H Amick Deborah D Gramajo Hugo H Tsai Shiou-Chuan SC

Biochemistry 20100801 34

The first committed step of fatty acid and polyketides biosynthesis, the biotin-dependent carboxylation of an acyl-CoA, is catalyzed by acyl-CoA carboxylases (ACCases) such as acetyl-CoA carboxylase (ACC) and propionyl-CoA carboxylase (PCC). ACC and PCC in Streptomyces coelicolor are homologue multisubunit complexes that can carboxylate different short chain acyl-CoAs. While ACC is able to carboxylate acetyl-, propionyl-, or butyryl-CoA with approximately the same specificity, PCC only recognize ...[more]

PMID: 20690600

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Project description:UnlabelledPupylation is a posttranslational modification peculiar to actinobacteria wherein proteins are covalently modified with a small protein called the prokaryotic ubiquitin-like protein (Pup). Like ubiquitination in eukaryotes, this phenomenon has been associated with proteasome-mediated protein degradation in mycobacteria. Here, we report studies of pupylation in a streptomycete that is phylogentically related to mycobacteria. We constructed mutants of Streptomyces coelicolor lacking PafA (Pup ligase), the proteasome, and the Pup-proteasome system. We found that these mutants share a high susceptibility to oxidative stress compared to that of the wild-type strain. Remarkably, we found that the pafA null mutant has a sporulation defect not seen in strains lacking the Pup-proteasome system. In proteomics experiments facilitated by an affinity-tagged variant of Pup, we identified 110 pupylated proteins in S. coelicolor strains having and lacking genes encoding the 20S proteasome. Our findings shed new light on this unusual posttranslational modification and its role in Streptomyces physiology.ImportanceThe presence of 20S proteasomes reminiscent of those in eukaryotes and a functional equivalent of ubiquitin, known as the prokaryotic ubiquitin-like protein (Pup), in actinobacteria have motivated reevaluations of protein homeostasis in prokaryotes. Though the Pup-proteasome system has been studied extensively in mycobacteria, it is much less understood in streptomycetes, members of a large genus of actinobacteria known for highly choreographed life cycles in which phases of morphological differentiation, sporulation, and secondary metabolism are often regulated by protein metabolism. Here, we define constituents of the pupylome in Streptomyces coelicolor for the first time and present new evidence that links pupylation and the oxidative stress response in this bacterium. Surprisingly, we found that the Pup ligase has a Pup-independent role in sporulation.

Dataset Information

Crystal structures and mutational analyses of acyl-CoA carboxylase beta subunit of Streptomyces coelicolor.

Publications

Crystal structures and mutational analyses of acyl-CoA carboxylase beta subunit of Streptomyces coelicolor.

Similar Datasets

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