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Lid mobility in lipase SMG1 validated using a thiol/disulfide redox potential probe.

ABSTRACT: Most lipases possess a lid domain above the catalytic site that is responsible for their activation. Lipase SMG1 from Malassezia globose CBS 7966 (Malassezia globosa LIP1), is a mono- and diacylglycerol lipase with an atypical loop-like lid domain. Activation of SMG1 was proposed to be solely through a gating mechanism involving two residues (F278 and N102). However, through disulfide bond cross-linking of the lid, this study shows that full activation also requires mobility of the lid domain, contrary to a previous proposal. The newly introduced disulfide bond makes lipase SMG1 eligible as a ratiometric thiol/disulfide redox potential probe, when it is coupled with chromogenic substrates. This redox-switch lipase could also be of potential use in cascade biocatalysis.

SUBMITTER: Guo S

PROVIDER: S-EPMC4856426 | biostudies-literature | 2016 May

REPOSITORIES: biostudies-literature

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Lid mobility in lipase SMG1 validated using a thiol/disulfide redox potential probe.

Guo Shaohua S Popowicz Grzegorz Maria GM Li Daoming D Yuan Dongjuan D Wang Yonghua Y

FEBS open bio 20160413 5

Most lipases possess a lid domain above the catalytic site that is responsible for their activation. Lipase SMG1 from Malassezia globose CBS 7966 (Malassezia globosa LIP1), is a mono- and diacylglycerol lipase with an atypical loop-like lid domain. Activation of SMG1 was proposed to be solely through a gating mechanism involving two residues (F278 and N102). However, through disulfide bond cross-linking of the lid, this study shows that full activation also requires mobility of the lid domain, c ...[more]

PMID: 27419053

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Project description:We previously identified a novel thiol-disulfide oxidoreductase, SdbA, in Streptococcus gordonii that formed disulfide bonds in substrate proteins and played a role in multiple phenotypes. In this study, we used mutational, phenotypic, and biochemical approaches to identify and characterize the redox partners of SdbA. Unexpectedly, the results showed that SdbA has multiple redox partners, forming a complex oxidative protein-folding pathway. The primary redox partners of SdbA that maintain its active site in an oxidized state are a surface-exposed thioredoxin family lipoprotein called SdbB (Sgo_1171) and an integral membrane protein annotated as CcdA2. Inactivation of sdbB and ccdA2 simultaneously, but not individually, recapitulated the sdbA mutant phenotype. The sdbB-ccdA2 mutant had defects in a range of cellular processes, including autolysis, bacteriocin production, genetic competence, and extracellular DNA (eDNA) release. AtlS, the natural substrate of SdbA produced by the sdbB-ccdA2 mutant lacked activity and an intramolecular disulfide bond. The redox state of SdbA in the sdbB-ccdA2 mutant was found to be in a reduced form and was restored when sdbB and ccdA2 were knocked back into the mutant. In addition, we showed that SdbB formed a disulfide-linked complex with SdbA in the cell. Recombinant SdbB and CcdA2 exhibited oxidase activity and reoxidized reduced SdbA in vitro Collectively, our results demonstrate that S. gordonii uses multiple redox partners for oxidative protein folding.IMPORTANCEStreptococcus gordonii is a commensal bacterium of the human dental plaque. Previously, we identified an enzyme, SdbA, that forms disulfide bonds in substrate proteins and plays a role in a number of cellular processes in S. gordonii Here, we identified the redox partners of SdbA. We showed that SdbA has multiple redox partners, SdbB and CcdA2, forming a complex oxidative protein-folding pathway. This pathway is essential for autolysis, bacteriocin production, genetic competence, and extracellular DNA (eDNA) release in S. gordonii These cellular processes are considered to be important for the success of S. gordonii as a dental plaque organism. This is the first example of an oxidative protein-folding pathway in Gram-positive bacteria that consists of an enzyme that uses multiple redox partners to function.

Dataset Information

Lid mobility in lipase SMG1 validated using a thiol/disulfide redox potential probe.

Publications

Lid mobility in lipase SMG1 validated using a thiol/disulfide redox potential probe.

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