Complete genome sequence of the Crohn's disease-associated adherent-invasive Escherichia coli strain HM605

Adherent-invasive Escherichia coli strains are increasingly being associated with intestinal pathologies. Here we present the genome sequence of E. coli HM605, a strain isolated from colonic biopsy specimens of a patient with Crohn's disease.     

An analysis of type-III secretion gene clusters in Chromobacterium violaceum

Chromobacterium violaceum is an environmental Gram-negative bacterium that is common in soil and water in tropical and sub-tropical regions. It is also a model organism for studying quorum-sensing and is a rare but deadly human pathogen. Recent completion of the genome sequence of C. violaceum strain ATCC 12472 revealed the presence of genes associated with type-III secretion systems (TTSSs). One of these systems resembles the Spi-1 system found in Salmonella enterica, whereas another is similar to the Spi-2 system from the same organism. Here, we present a detailed analysis and a fresh annotation of the two gene clusters. Moreover, we highlight the presence of several genes encoding putative type-III effector proteins that lead us to predict that this organism can manipulate vesicular trafficking, the actin cytoskeleton and apoptotic pathways within mammalian cells to its own advantage.     

The ESAT-6/WXG100 superfamily -- and a new Gram-positive secretion system?

ESAT-6 is a small secreted protein of unknown function from Mycobacterium tuberculosis that is of fundamental importance in virulence and protective immunity. A PSI-BLAST search has identified distant homologues of ESAT-6 in more tractable bacteria, including Bacillus subtilis, Bacillus anthracis, Staphylococcus aureus and Clostridium acetobutylicum. The genes for ESAT-6-like proteins often cluster with genes encoding homologues of B. subtilis YukA. I speculate that the ESAT-6-like and YukA-like proteins form a novel Gram-positive secretion system potentially driven by the FtsK/SpoIIIE ATPase domains in the YukA-like proteins. The way is now open to investigate this hypothesis in organisms that are easier to manipulate than pathogenic mycobacteria.     

Demonstration of different metal ion-induced calcineurin conformations using a monoclonal antibody

It has been suggested that calcineurin, a calmodulin-stimulated phosphatase, may exist in different metal ion-dependent conformational states (Pallen, C.J., and Wang, J. H. (1984) J. Biol. Chem. 259, 6134-6141). Evidence in favor of this hypothesis comes from studies involving a monoclonal antibody, VA1, which is specific for the small (beta) subunit of calcineurin. This antibody inhibits Ni2+-stimulated but not Mn2+-stimulated phosphatase activity against p-nitrophenyl phosphate and phosphorylase kinase. Inhibition is not due to competition of the antibody with substrate or to interference with metal ion binding to the enzyme. Complex formation between the antibody and calcineurin can be demonstrated either in the presence of Mn2+ or Ni2+ or in the absence of metal ion activators. These results indicate that the active conformational states of calcineurin are metal ion dependent, that the monoclonal antibody VA1 affects the Ni2+-induced conformational change of the enzyme, and that the beta subunit of calcineurin plays a critical role in the expression of Ni2+-stimulated phosphatase activity.     

Introducing the Internet.

The benefits to medical practitioners of using the Internet are growing rapidly as the Internet becomes easier to use and ever more biomedical resources become available on line. The Internet is the largest computer network in the world; it is also a virtual community, larger than many nation states, with its own rules of behaviour or "netiquette." There are several types of Internet connection and various ways of acquiring a connection. Once connected, you can obtain, free of charge, programs that allow easy use of the Internet''s resources and help on how to use these resources; you can access many of these resources through the hypertext references in the on line version of this series (go to http:@www.bmj.com/bmj/ to reach the electronic version). You can then explore the various methods for accessing, manipulating, or disseminating data on the Internet, such as electronic mail, telnet, file transfer protocol, and the world wide web. Results from a search of the world wide web for information on the rare condition of Recklinghausen''s neurofibromatosis illustrate the breadth of medical information available on the Internet.     

Electronic mail.

Electronic mail (email) has many advantages over other forms of communication: it is easy to use, free of charge, fast, and delivers information in a digital format. As a text only medium, email is usually less formal in style than conventional correspondence and may contain acronyms and other features, such as smileys, that are peculiar to the Internet. Email client programs that run on your own microcomputer render email powerful and easy to use. With suitable encoding methods, email can be used to send any kind of computer file, including pictures, sounds, programs, and movies. Numerous biomedical electronic mailing lists and other Internet services are accessible by email.