@article {38247,
	title = {Exopolysaccharide-associated protein sorting in environmental organisms: the PEP-CTERM/EpsH system. Application of a novel phylogenetic profiling heuristic},
	journal = {BMC biologyBMC biology},
	volume = {4},
	year = {2006},
	note = {http://www.ncbi.nlm.nih.gov/pubmed/16930487?dopt=Abstract},
	type = {10.1186/1741-7007-4-29},
	abstract = {BACKGROUND: Protein translocation to the proper cellular destination may be guided by various classes of sorting signals recognizable in the primary sequence. Detection in some genomes, but not others, may reveal sorting system components by comparison of the phylogenetic profile of the class of sorting signal to that of various protein families. RESULTS: We describe a short C-terminal homology domain, sporadically distributed in bacteria, with several key characteristics of protein sorting signals. The domain includes a near-invariant motif Pro-Glu-Pro (PEP). This possible recognition or processing site is followed by a predicted transmembrane helix and a cluster rich in basic amino acids. We designate this domain PEP-CTERM. It tends to occur multiple times in a genome if it occurs at all, with a median count of eight instances; Verrucomicrobium spinosum has sixty-five. PEP-CTERM-containing proteins generally contain an N-terminal signal peptide and exhibit high diversity and little homology to known proteins. All bacteria with PEP-CTERM have both an outer membrane and exopolysaccharide (EPS) production genes. By a simple heuristic for screening phylogenetic profiles in the absence of pre-formed protein families, we discovered that a homolog of the membrane protein EpsH (exopolysaccharide locus protein H) occurs in a species when PEP-CTERM domains are found. The EpsH family contains invariant residues consistent with a transpeptidase function. Most PEP-CTERM proteins are encoded by single-gene operons preceded by large intergenic regions. In the Proteobacteria, most of these upstream regions share a DNA sequence, a probable cis-regulatory site that contains a sigma-54 binding motif. The phylogenetic profile for this DNA sequence exactly matches that of three proteins: a sigma-54-interacting response regulator (PrsR), a transmembrane histidine kinase (PrsK), and a TPR protein (PrsT). CONCLUSION: These findings are consistent with the hypothesis that PEP-CTERM and EpsH form a protein export sorting system, analogous to the LPXTG/sortase system of Gram-positive bacteria, and correlated to EPS expression. It occurs preferentially in bacteria from sediments, soils, and biofilms. The novel method that led to these findings, partial phylogenetic profiling, requires neither global sequence clustering nor arbitrary similarity cutoffs and appears to be a rapid, effective alternative to other profiling methods.},
	keywords = {Amino Acid Motifs, Amino Acid Sequence, bacteria, Bacterial Proteins, Biofilms, Genome, Bacterial, Markov chains, Molecular Sequence Data, Phylogeny, Polysaccharides, Bacterial, Protein Sorting Signals, Protein Transport, Seawater, sequence alignment, Soil Microbiology},
	author = {Haft, Daniel H. and Paulsen, Ian T. and Ward, Naomi and J. Selengut}
}
@article {38536,
	title = {The transcription factor Eyes absent is a protein tyrosine phosphatase},
	journal = {NatureNature},
	volume = {426},
	year = {2003},
	note = {http://www.ncbi.nlm.nih.gov/pubmed/14628053?dopt=Abstract},
	type = {10.1038/nature02097},
	abstract = {Post-translational modifications provide sensitive and flexible mechanisms to dynamically modulate protein function in response to specific signalling inputs. In the case of transcription factors, changes in phosphorylation state can influence protein stability, conformation, subcellular localization, cofactor interactions, transactivation potential and transcriptional output. Here we show that the evolutionarily conserved transcription factor Eyes absent (Eya) belongs to the phosphatase subgroup of the haloacid dehalogenase (HAD) superfamily, and propose a function for it as a non-thiol-based protein tyrosine phosphatase. Experiments performed in cultured Drosophila cells and in vitro indicate that Eyes absent has intrinsic protein tyrosine phosphatase activity and can autocatalytically dephosphorylate itself. Confirming the biological significance of this function, mutations that disrupt the phosphatase active site severely compromise the ability of Eyes absent to promote eye specification and development in Drosophila. Given the functional importance of phosphorylation-dependent modulation of transcription factor activity, this evidence for a nuclear transcriptional coactivator with intrinsic phosphatase activity suggests an unanticipated method of fine-tuning transcriptional regulation.},
	keywords = {Amino Acid Motifs, Amino Acid Sequence, Animals, Antibodies, Phospho-Specific, Drosophila melanogaster, Drosophila Proteins, Embryonic Induction, eye, Eye Proteins, Gene Expression Regulation, Kinetics, Mice, Models, Molecular, Molecular Sequence Data, Mutation, Phosphorylation, Protein Conformation, Protein Tyrosine Phosphatases, Substrate Specificity, Transcription Factors},
	author = {Tootle, Tina L. and Silver, Serena J. and Davies, Erin L. and Newman, Victoria and Latek, Robert R. and Mills, Ishara A. and J. Selengut and Parlikar, Beth E. W. and Rebay, Ilaria}
}
@article {38368,
	title = {MDP-1 is a new and distinct member of the haloacid dehalogenase family of aspartate-dependent phosphohydrolases},
	journal = {BiochemistryBiochemistry},
	volume = {40},
	year = {2001},
	note = {http://www.ncbi.nlm.nih.gov/pubmed/11601995?dopt=Abstract},
	abstract = {MDP-1 is a eukaryotic magnesium-dependent acid phosphatase with little sequence homology to previously characterized phosphatases. The presence of a conserved motif (Asp-X-Asp-X-Thr) in the N terminus of MDP-1 suggested a relationship to the haloacid dehalogenase (HAD) superfamily, which contains a number of magnesium-dependent acid phosphatases. These phosphatases utilize an aspartate nucleophile and contain a number of conserved active-site residues and hydrophobic patches, which can be plausibly aligned with conserved residues in MDP-1. Seven site-specific point mutants of MDP-1 were produced by modifying the catalytic aspartate, serine, and lysine residues to asparagine or glutamate, alanine, and arginine, respectively. The activity of these mutants confirms the assignment of MDP-1 as a member of the HAD superfamily. Detailed comparison of the sequence of the 15 MDP-1 sequences from various organisms with other HAD superfamily sequences suggests that MDP-1 is not closely related to any particular member of the superfamily. The crystal structures of several HAD family enzymes identify a domain proximal to the active site responsible for important interactions with low molecular weight substrates. The absence of this domain or any other that might perform the same function in MDP-1 suggests an "open" active site capable of interactions with large substrates such as proteins. This suggestion was experimentally confirmed by demonstration that MDP-1 is competent to catalyze the dephosphorylation of tyrosine-phosphorylated proteins.},
	keywords = {Amino Acid Motifs, Amino Acid Sequence, Animals, Aspartic Acid, Catalytic Domain, HUMANS, Hydrolases, Mice, Molecular Sequence Data, Multigene Family, Mutagenesis, Site-Directed, Phosphoprotein Phosphatases, Protein Structure, Tertiary, Protein Tyrosine Phosphatases, Rats, Saccharomyces cerevisiae, sequence alignment, Sequence Homology, Amino Acid},
	author = {J. Selengut}
}
