Biosynthesis in Enterobacteriaceae

Department of Microbiology, Tumor and Cell Biology (MTC), Box 280, Karolinska Institutet, SE-17177 Stockholm, Sweden 

Curli fimbriae, electron microscopy, environmental conditions, Escherichia coli, GGDEF domain, ompR, regulation, rpoS, Salmonella typhimurium, thin aggregative fimbriae. 

Recently, enzymatic and chemical analysis in combination with genetic studies revealed that Salmonella enterica serotype Typhimurium (S. typhimurium) is capable to produce cellulose as an exopolysaccharide (Zogaj et al. 2001). The 

Saxena (edx), Cellulose Molecular and Structural Biology, 107-122. 2007 Springer, 

Cellulose production confers bacterial cell-cell interactions, adhesion to abiotic surfaces (biofilm formation) and chlorine resistance to the organism (Romling et al. 2000 Zogaj et al. 2001 Solano et al. 2002). Beginning studies shed some light on the molecular mechanisms of cellulose biosynthesis and regulation in S. typhimurium and the epidemiology of cellulose biosynthesis in Enterobacteriaceae. 

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Recently, the molecular basis of cellulose biosynthesis has been detected in S. typhimurium and other Enterobacteriaceae. With this discovery, however, new questions did arise concerning various aspects such as the mode of cellulose biosynthesis, its regulation, function, epidemiology, structure and interaction of cellulose with other components. At present, answers are only partially available, if at all. The availability of well characterized and fully sequenced strains together with efficient tools for genetic manipulation, however, gives hope that fairly soon light will be shed at least to some aspects of cellulose biosynthesis in Enterobacteriaceae. 

Romling U. and Lunsdorf H. 2003. Cellulose biosynthesis in Enterobacteriaceae. Cellulose 11 413 18. 

The NMNAT activity was originally inferred by bioinformatics analysis and experimentally identified for the central domain (aa 64—234) of the multifunctional NadR protein from E. coli. The three-domain version of the NadR protein that exists only in Enterobacteriaceae contains an N-terminal HTH domain, which is involved in DNA binding, mediating its role as a transcriptional regulator of NAD biosynthesis (see Section... 

BcsQ which is required for cellulose biosynthesis in vivo, is part of the cellulose biosynthesis operon in Enterobacteriaceae and G. xylinus. BcsC contains a N-terminal membrane domain and several tetratrico peptide repeats (TRPs) motifs, indicating that it might participate in protein-protein interactions. 

On this basis, the proteins of riboflavin biosynthesis may be relevant targets for the development of novel antibacterial agents, notably with selectivity for mycobacteria, Enterobacteriaceae, or pathogenic yeasts. Since these proteins are absent in human and animal hosts, the risks of off-target toxicity should be comparatively low. 

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