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Archaea
Volume 2010, Article ID 410975, 11 pages
http://dx.doi.org/10.1155/2010/410975
Research Article

Mutational and Bioinformatic Analysis of Haloarchaeal Lipobox-Containing Proteins

1Department of Biology, University of Pennsylvania, Philadelphia, PA 19104-6018, USA
2Department of Membrane Biochemistry, Max-Planck-Institute of Biochemistry, Martinsried 82152, Germany
3Graduate Group in Genomics and Computational Biology, University of Pennsylvania, Philadelphia, PA 19104-6018, USA
4Program in Cellular and Molecular Biology, University of Wisconsin-Madison, Madison, WI 53706, USA

Received 18 May 2010; Revised 4 July 2010; Accepted 12 July 2010

Academic Editor: Jerry Eichler

Copyright © 2010 Stefanie Storf et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A conserved lipid-modified cysteine found in a protein motif commonly referred to as a lipobox mediates the membrane anchoring of a subset of proteins transported across the bacterial cytoplasmic membrane via the Sec pathway. Sequenced haloarchaeal genomes encode many putative lipoproteins and recent studies have confirmed the importance of the conserved lipobox cysteine for signal peptide processing of three lipobox-containing proteins in the model archaeon Haloferax volcanii. We have extended these in vivo analyses to additional Hfx. volcanii substrates, supporting our previous in silico predictions and confirming the diversity of predicted Hfx. volcanii lipoproteins. Moreover, using extensive comparative secretome analyses, we identified genes encodining putative lipoproteins across a wide range of archaeal species. While our in silico analyses, supported by in vivo data, indicate that most haloarchaeal lipoproteins are Tat substrates, these analyses also predict that many crenarchaeal species lack lipoproteins altogether and that other archaea, such as nonhalophilic euryarchaeal species, transport lipoproteins via the Sec pathway. To facilitate the identification of genes that encode potential haloarchaeal Tat-lipoproteins, we have developed TatLipo, a bioinformatic tool designed to detect lipoboxes in haloarchaeal Tat signal peptides. Our results provide a strong foundation for future studies aimed at identifying components of the archaeal lipoprotein biogenesis pathway.