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In this study, flavohemoproteins from protist, bacterial and fungal sources as well those available in metagenome data have been characterized using standard bioinformatics tools in order to study their phylogenetic relationships, three-dimensional structure and functional parameters. 5 clusters of metagenomic proteins were identified which showed the closest neighbors with known genera. The average length of flavohemoprotein in the data set was found to be 414 residues. The average pI and molecular weight (MW) was 6.72 and 47.28 kDa respectively in all strains including metagenome sequences. Flavohemoproteins showed similar amino acid composition among different organisms including proteins from metagenomic data and from known genera, with relative higher abundance of amino acids Ala and Leu. The secondary structure prediction results revealed that the enzymes are dominated by α-helices and random coils. Tertiary structure analysis revealed the presence of three ligand binding sites for Heme, FAD and NAD. The computational analysis of flavohemoproteins from metagenomic data done in this study can provide useful sequence and structural information which can be further used for metaproteomic analysis in search for novel flavohemoprotein enzymes from the environment. [ABSTRACT FROM AUTHOR]

The ADP-ribosylating toxins (ADPRTs) are a family of toxins that catalyse the hydrolysis of NAD and the transfer of the ADP-ribose moiety onto a target. This family includes many notorious killers, responsible for thousands of deaths annually including: cholera, enterotoxic Escherichia coli, whooping cough, diphtheria and a plethora of Clostridial binary toxins. Despite their notoriety as pathogens, the ADPRTs have been extensively used as cellular tools to study and elucidate the functions of the small GTPases that they target. There are four classes of ADPRTs and at least one structure representative of each of these classes has been determined. They all share a common fold and several motifs around the active site that collectively facilitate the binding and transfer of the ADP-ribose moiety of NAD to their protein targets. In this review, we present an overview of the physiology and cellular qualities of the bacterial ADPRTs and take an in-depth look at the structural motifs that differentiate the different classes of bacterial ADPRTs in relation to their function. [ABSTRACT FROM AUTHOR]

L-myo-Inositol 1-phosphate synthase (MIPS, EC 5.5.1.4), the key enzyme in the inositol and phosphoinositide biosynthetic pathway, is present throughout evolutionarily diverse organisms and is considered an ancient protein/gene. Analysis by multiple sequence alignment, phylogenetic tree generation and comparison of newly determined crystal structures provides new insight into the origin and evolutionary relationships among the various MIPS proteins/genes. The evolution of the MIPS protein/gene among the prokaryotes seems more diverse and complex than amongst the eukaryotes. However, conservation of a ‘core catalytic structure’ among the MIPS proteins implies an essential function of the enzyme in cellular metabolism throughout the biological kingdom. [Copyright &y& Elsevier]