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Structure of rhomboid protease in a lipid environment.

ABSTRACT: Structures of the prokaryotic homologue of rhomboid proteases reveal a core of six transmembrane helices, with the active-site residues residing in a hydrophilic cavity. The native environment of rhomboid protease is a lipid bilayer, yet all the structures determined thus far are in a nonnative detergent environment. There remains a possibility of structural artefacts arising from the use of detergents. In an attempt to address the effect of detergents on the structure of rhomboid protease, crystals of GlpG, an Escherichia coli rhomboid protease in a lipid environment, were obtained using two alternative approaches. The structure of GlpG refined to 1. 7-Å resolution was obtained from crystals grown in the presence of lipid bicelles. This structure reveals well-ordered and partly ordered lipid molecules forming an annulus around the protein. Lipid molecules adapt to the surface features of protein and arrange such that they match the hydrophobic thickness of GlpG. Virtually identical two-dimensional crystals were also obtained after detergent removal by dialysis. A comparison of an equivalent structure determined in a completely delipidated detergent environment provides insights on how detergent substitutes for lipid. A detergent molecule is also observed close to the active site, helping to postulate a model for substrate binding and hydrolysis in rhomboids.

SUBMITTER: Vinothkumar KR

PROVIDER: S-EPMC3093617 | biostudies-literature | 2011 Mar

REPOSITORIES: biostudies-literature

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Structure of rhomboid protease in a lipid environment.

Vinothkumar Kutti R KR

Journal of molecular biology 20110119 2

Structures of the prokaryotic homologue of rhomboid proteases reveal a core of six transmembrane helices, with the active-site residues residing in a hydrophilic cavity. The native environment of rhomboid protease is a lipid bilayer, yet all the structures determined thus far are in a nonnative detergent environment. There remains a possibility of structural artefacts arising from the use of detergents. In an attempt to address the effect of detergents on the structure of rhomboid protease, crys ...[more]

PMID: 21256137

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Project description:BackgroundPlasmodium vivax infection remains a major public health problem, especially along the Thailand border regions. We examined the genetic diversity of this parasite by analyzing single-nucleotide polymorphisms (SNPs) of the P. vivax rhomboid-like protease 1 gene (Pvrom1) in parasites collected from western (Tak province, Thai-Myanmar border) and eastern (Chanthaburi province, Thai-Cambodia border) regions.MethodsData were collected by a cross-sectional survey, consisting of 47 and 45 P. vivax-infected filter paper-spotted blood samples from the western and eastern regions of Thailand, respectively during September 2013 to May 2014. Extracted DNA was examined for presence of P. vivax using Plasmodium species-specific nested PCR. Pvrom1 gene was PCR amplified, sequenced and the SNP diversity was analyzed using F-STAT, DnaSP, MEGA and LIAN programs.ResultsComparison of sequences of the 92 Pvrom1 831-base open reading frames with that of a reference sequence (GenBank acc. no. XM001615211) revealed 17 samples with a total of 8 polymorphic sites, consisting of singleton (exon 3, nt 645) and parsimony informative (exon 1, nt 22 and 39; exon 3, nt 336, 537 and 656; and exon 4, nt 719 and 748) sites, which resulted in six different deduced Pvrom1 variants. Non-synonymous to synonymous substitutions ratio estimated by the DnaSP program was 1.65 indicating positive selection, but the Z-tests of selection showed no significant deviations from neutrality for Pvrom1 samples from western region of Thailand. In addition McDonald Kreitman test (MK) showed not significant, and Fst values are not different between the two regions and the regions combined. Interestingly, only Pvrom1 exon 2 was the most conserved sequences among the four exons.ConclusionsThe relatively high degree of Pvrom1 polymorphism suggests that the protein is important for parasite survival in face of changes in both insect vector and human populations. These polymorphisms could serve as a sensitive marker for studying plasmodial genetic diversity. The significance of Pvrom1 conserved exon 2 sequence remains to be investigated.

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Structure of rhomboid protease in a lipid environment.

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Structure of rhomboid protease in a lipid environment.

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