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The scc spirochetal coiled-coil protein forms helix-like filaments and binds to nucleic acids generating nucleoprotein structures.

ABSTRACT: The analysis of the genome of Leptospira spp., a group of bacteria of the phylum of spirochetes with several unique evolutionary and morphological features, has allowed the identification of a gene encoding a coiled-coil protein, called Scc, which is completely unrelated to any other eukaryotic or prokaryotic protein. Since coiled-coil proteins are often key elements of the cytoskeleton, we analyzed the protein Scc, which is a 24-kDa protein composed of a N-terminal coiled-coil domain, a proline-rich intermediate domain, and an acidic tail. The gene scc is located in an operon which also contains the genes encoding the initiation factor IF3 and the two ribosomal proteins L20 and L35. In this study, we showed that the presence of the coiled-coil domain was responsible for the polymerization of Scc in helix-like structures, in an ATP-independent manner, in both Escherichia coli living cells and in vitro. Analysis of the Scc polymers by electron microscopy showed filaments with a width of 6 to 10 nm, similar to that of eukaryotic intermediate filaments. Scc was also found to bind both RNA and double-stranded DNA without detectable sequence specificity. By electron microscopy, we showed that Scc polymer assembly was affected by the presence of nucleic acids, giving rise to rod-shaped structures with a width ranging from 45 to 155 nm. Finally, Leptospira biflexa cells depleted in Scc form small colonies, but the morphology of their helicoidal cell body was not affected. These results provide the first insight into a unique DNA binding filament-forming coiled-coil protein that could play an important role in the subcellular architecture of the spirochetal microorganism.

SUBMITTER: Mazouni K

PROVIDER: S-EPMC1347299 | biostudies-literature | 2006 Jan

REPOSITORIES: biostudies-literature

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The scc spirochetal coiled-coil protein forms helix-like filaments and binds to nucleic acids generating nucleoprotein structures.

Mazouni Khalil K Pehau-Arnaudet Gérard G England Patrick P Bourhy Pascale P Saint Girons Isabelle I Picardeau Mathieu M

Journal of bacteriology 20060101 2

The analysis of the genome of Leptospira spp., a group of bacteria of the phylum of spirochetes with several unique evolutionary and morphological features, has allowed the identification of a gene encoding a coiled-coil protein, called Scc, which is completely unrelated to any other eukaryotic or prokaryotic protein. Since coiled-coil proteins are often key elements of the cytoskeleton, we analyzed the protein Scc, which is a 24-kDa protein composed of a N-terminal coiled-coil domain, a proline ...[more]

PMID: 16385037

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Project description:The alpha-helical coiled coil is a structurally simple protein oligomerization or interaction motif consisting of two or more alpha helices twisted into a supercoiled bundle. Coiled coils can differ in their stoichiometry, helix orientation, and axial alignment. Because of the near degeneracy of many of these variants, coiled coils pose a challenge to fold recognition methods for structure prediction. Whereas distinctions between some protein folds can be discriminated on the basis of hydrophobic/polar patterning or secondary structure propensities, the sequence differences that encode important details of coiled-coil structure can be subtle. This is emblematic of a larger problem in the field of protein structure and interaction prediction: that of establishing specificity between closely similar structures. We tested the behavior of different computational models on the problem of recognizing the correct orientation--parallel vs. antiparallel--of pairs of alpha helices that can form a dimeric coiled coil. For each of 131 examples of known structure, we constructed a large number of both parallel and antiparallel structural models and used these to assess the ability of five energy functions to recognize the correct fold. We also developed and tested three sequence-based approaches that make use of varying degrees of implicit structural information. The best structural methods performed similarly to the best sequence methods, correctly categorizing approximately 81% of dimers. Steric compatibility with the fold was important for some coiled coils we investigated. For many examples, the correct orientation was determined by smaller energy differences between parallel and antiparallel structures distributed over many residues and energy components. Prediction methods that used structure but incorporated varying approximations and assumptions showed quite different behaviors when used to investigate energetic contributions to orientation preference. Sequence based methods were sensitive to the choice of residue-pair interactions scored.

Dataset Information

The scc spirochetal coiled-coil protein forms helix-like filaments and binds to nucleic acids generating nucleoprotein structures.

Publications

The scc spirochetal coiled-coil protein forms helix-like filaments and binds to nucleic acids generating nucleoprotein structures.

Similar Datasets

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