Analysis ofN-acetylglucosamine metabolism in the marine bacteriumPirellulasp. strain 1 by a proteomic approach

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Abstract
Pirellula sp. strain 1 is a marine bacterium that can grow with the chitin monomer N-acetylglucosamine as sole source of carbon and nitrogen under aerobic conditions, and that is a member of the bacterial phylum Planctomycetes. As a basis for the proteomic studies we quantified growth of strain 1 with N-acetylglucosamine and glucose, revealing doubling times of 14 and 10 h, respectively. Studies with dense cell suspensions indicated that the capacity to degrade N-acetylglucosamine and glucose may not be tightly regulated. Proteins from soluble extracts prepared from exponential cultures grown either with N-acetylglucosamine or glucose were separated by two-dimensional gel electrophoresis and visualized by fluorescence staining (Sypro® Ruby). Analysis of the protein patterns revealed the presence of several protein spots only detectable in soluble extracts of N-acetylglucosamine grown cells. Determination of amino acid sequences and peptide mass fingerprints from tryptic fragments of the most abundant one of these spots allowed the identification of the coding gene on the genomic sequence of Pirellula sp. strain 1. This gene showed similarities to a dehydrogenase from Bacillus subtilis, and is closely located to a gene similar to glucosamine-6-phosphate isomerase from B. subtilis. Genes of two other proteins expressed during growth on N-acetylglucosamine as well as on glucose were also identified and found to be similar to a glyceraldehyde-3-phosphate-dehydrogenase and a NADH-dehydrogenase, respectively. Thus the coding genes of three proteins expressed during growth of Pirellula sp. strain 1 on carbohydrates were identified and related by sequence similarity to carbohydrate metabolism.