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A novel role for antifreeze proteins (AFPs) may reside in an exceptionally large 1.5-MDa adhesin isolated from an Antarctic Gram-negative bacterium, Marinomonas primoryensis. MpAFP was purified from bacterial lysates by ice adsorption and gel electrophoresis. We have previously reported that two highly repetitive sequences, region II (RII) and region IV (RIV), divide MpAFP into five distinct regions, all of which require mM Ca(2+) levels for correct folding. Also, the antifreeze activity is confined to the 322-residue RIV, which forms a Ca(2+)-bound beta-helix containing thirteen Repeats-In-Toxin (RTX)-like repeats. RII accounts for approximately 90% of the mass of MpAFP and is made up of ∼120 tandem 104-residue repeats. Because these repeats are identical in DNA sequence, their number was estimated here by pulsed-field gel electrophoresis. Structural homology analysis by the Protein Homology/analogY Recognition Engine (Phyre2) server indicates that the 104-residue RII repeat adopts an immunoglobulin beta-sandwich fold that is typical of many secreted adhesion proteins. Additional RTX-like repeats in RV may serve as a non-cleavable signal sequence for the type I secretion pathway. Immunodetection shows both repeated regions are uniformly distributed over the cell surface. We suggest that the development of an AFP-like domain within this adhesin attached to the bacterial outer surface serves to transiently bind the host bacteria to ice. This association would keep the bacteria within the upper reaches of the water column where oxygen and nutrients are potentially more abundant. This novel envirotactic role would give AFPs a third function, after freeze avoidance and freeze tolerance: that of transiently binding an organism to ice.
Pubmed ID: 23144980
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A collection of both commercial and noncommercial software products which includes: Mascot Distiller, Mascot Parser, and Mascot Server. Mascot Distiller is commercial and provides a single interface to process raw data into de-isotoped peak lists. This tool can also be used for the easy distribution of search and quantitative results to colleagues. The non-commercial Mascot Parser software provides an API (Application Programmer Interface) that makes it easier to access search results written in C++, Java, Python and Perl. Mascot Server is non-commercial, and is a collection of peptide mass fingerprints as well as a MS/MS database. A selection of popular sequence databases are available online and include SwissProt, NCBInr, and the EST divisions of EMBL. This server is best used for evaluating and searching for smaller data sets.
View all literature mentionsNSERC aims to make Canada a country of discoverers and innovators for the benefit of all Canadians. The agency supports university students in their advanced studies, promotes and supports discovery research, and fosters innovation by encouraging Canadian companies to participate and invest in postsecondary research projects. NSERC researchers are on the vanguard of science, building on Canada''s long tradition of scientific excellence.
View all literature mentionsThe Canadian Institutes of Health Research (CIHR) is the Government of Canada''s agency responsible for funding health research in Canada. CIHR was created in 2000 under the authority of the CIHR Act and reports to Parliament through the Minister of Health. CIHR''s budget for 2008-09 is $928.6 million, of which $132 million is allocated to administering the Networks of Centres of Excellence and Canada Research Chair programs. CIHR was created to transform health research in Canada by: * funding more research on targeted priority areas; * building research capacity in under-developed areas such as population health and health services research; * training the next generation of health researchers; and * focusing on knowledge translation, so that the results of research are transformed into policies, practices, procedures, products and services. CIHR consists of 13 virtual institutes, a structure that is unique in the world. These innovative institutes bring together all partners in the research process - the people who fund research, those who carry it out and those who use its results - to share ideas and focus on what Canadians need: good health and the means to prevent disease and fight it when it happens. Each institute supports a broad spectrum of research in its topic areas and, in consultation with its stakeholders, sets priorities for research in those areas.
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