The capsule polysaccharide structure and biogenesis for non-O1 Vibrio cholerae NRT36S: genes are embedded in the LPS region

Background  

In V. cholerae, the biogenesis of capsule polysaccharide is poorly understood. The elucidation of capsule structure and biogenesis is critical to understanding the evolution of surface polysaccharide and the internal relationship between the capsule and LPS in this species. V. cholerae serogroup O31 NRT36S, a human pathogen that produces a heat-stable enterotoxin (NAG-ST), is encapsulated. Here, we report the covalent structure and studies of the biogenesis of the capsule in V. cholerae NRT36S.     

Genomics and the renaissance of generalism

A meeting report of the sessions on human, eukaryotic and bacterial genome sequencing at the American Society for Microbiology and Institut Pasteur joint conference: Genomes 2000 International Conference on Microbial and Model Genomes, Paris, April 11-15, 2000     

Genetic control of alcohol dehydrogenase isozymes in maize

By means of horizontal gel electrophoresis and the zymogram technique, genetic variants and the formation of a hybrid molecule of the enzyme alcohol dehydrogenase (ADH) have been found in Zea mays. Each inbred homozygous stock examined showed two types of ADH isozyme patterns: a fast faint zone and a slower deeply staining zone, both anode-migrating at pH 8.5. The variants found differed in that each of the ADH zones varied in its electrophoretic mobility when compared to its counterpart in the other strain. When appropriate genetic crosses were made, the resulting heterozygotes showed the parental ADH zones, and, in addition, a band of intermediate mobility was formed between the deep-staining ADH bands. However, in the fast-moving zone only the parental isozymes were represented in the heterozygote. The formation of the hybrid molecule and the apparent gene dosage effects support the hypothesis that ADH-2 in maize exists as a dimer, whereas ADH-1 may exist as a monomer.This work was supported by the U.S. Atomic Energy Commission, under contract No. AT(11-1)-1338.     

Molecular biology of intracellular protein trafficking

The evidence accumulated to date indicates that protein compartmentalization is mediated through specific regions of proteins destined for translocation into subcellular organelles. Proteins targeted to mitochondria, chloroplasts or the endoplasmic reticulum have 'transit' sequences contained in amino-terminal peptide extensions. However, most peroxisomal proteins do not have amino-terminal extensions. Protein importation into mitochondria has been extensively studied and characterized. This post-translational process appears to involve receptors on the mitochondrial outer membrane, and is dependent upon the electrochemical gradient across the inner membrane. Translocation to one of the submitochondrial compartments is determined by the type of transit sequence contained in a mitochondrial protein. The majority of imported mitochondrial proteins are proteolytically altered prior to assembly into oligomeric enzyme complexes. Protein importation into peroxisomes is distinctly different from importation into mitochondria. Although both processes are post-translational, their only other similarity is a requirement for ATP. In this review, we present and compare recent evidence for both mitochondrial and peroxisomal protein importation.