@article {409, title = {Phylogenetic classification of diverse LysR-type transcriptional regulators of a model prokaryote Geobacter sulfurreducens.}, journal = {J Mol Evol}, volume = {74}, year = {2012}, month = {2012 Apr}, pages = {187-205}, abstract = {The protein family of LysR-type transcriptional regulators (LTTRs) is highly abundant among prokaryotes. We analyzed 10,145 non-redundant microbial sequences with homology to eight LysR family regulators of a model prokaryote, Geobacter sulfurreducens, and employed phylogenetic tree inference for LTTR classification. We also analyzed the arrangement of genome clusters containing G. sulfurreducens LTTR genes and searched for LTTR regulatory motifs, suggesting likely regulatory targets of G. sulfurreducens LTTRs. This is the first study to date providing a detailed classification of LTTRs in the deltaproteobacterial family Geobacteraceae.}, issn = {1432-1432}, doi = {10.1007/s00239-012-9498-z}, author = {Krushkal, Julia and Qu, Yanhua and Lovley, Derek R and Adkins, Ronald M} } @article {422, title = {Genome diversity of the TetR family of transcriptional regulators in a metal-reducing bacterial family Geobacteraceae and other microbial species.}, journal = {OMICS}, volume = {15}, year = {2011}, month = {2011 Jul-Aug}, pages = {495-506}, abstract = {Members of the TetR family of bacterial transcriptional regulators affect expression of genes whose products are involved in a variety of important functions, including osmotic stress, catabolic pathways, homeostasis, biosynthesis of antibiotics, expression of efflux pumps, multidrug resistance, and virulence of pathogenic bacteria. We used genome sequence information to carry out phylogenetic classification of 864 TetR family members with a special focus on TetR regulators in Geobacteraceae, an environmentally important family of delta-Proteobacteria. The genome of Geobacter sulfurreducens, a model representative of Geobacteraceae, contains nine genes from the tetR family. Several of these genes are located immediately upstream of operons encoding functionally important c-type cytochromes. Computational analyses identified the presence of conserved promoters and other regulatory binding sites upstream of several G. sulfurreducens tetR genes. This suggests the possibility of an intermediary role of TetR family proteins in Geobacteraceae in regulatory cascades involving a variety of sigma factors. In order to understand the role of the TetR regulatory family in Geobacteraceae, we have inferred phylogenetic relationships among the Geobacteraceae TetR proteins and their homologs in other microbial species.}, keywords = {Bacterial Proteins, Binding Sites, Gram-Negative Bacteria, Metals, Oxidation-Reduction, Phylogeny, Promoter Regions, Genetic, Sigma Factor}, issn = {1557-8100}, doi = {10.1089/omi.2010.0117}, author = {Krushkal, Julia and Sontineni, Sreedhar and Leang, Ching and Qu, Yanhua and Adkins, Ronald M and Lovley, Derek R} } @article {436, title = {Genome-wide survey for PilR recognition sites of the metal-reducing prokaryote Geobacter sulfurreducens.}, journal = {Gene}, volume = {469}, year = {2010}, month = {2010 Dec 1}, pages = {31-44}, abstract = {Geobacter sulfurreducens is a species from the bacterial family Geobacteraceae, members of which participate in bioenergy production and in environmental bioremediation. G. sulfurreducens pili are electrically conductive and are required for Fe(III) oxide reduction and for optimal current production in microbial fuel cells. PilR is an enhancer binding protein, which is an activator acting together with the alternative sigma factor, RpoN, in transcriptional regulation. Both RpoN and PilR are involved in regulation of expression of the pilA gene, whose product is pilin, a structural component of a pilus. Using bioinformatic approaches, we predicted G. sulfurreducens sequence elements that are likely to be regulated by PilR. The functional importance of the genome region containing a PilR binding site predicted upstream of the pilA gene was experimentally validated. The predicted G. sulfurreducens PilR binding sites are similar to PilR binding sites of Pseudomonas and Moraxella. While the number of predicted PilR-regulated sites did not deviate from that expected by chance, multiple sites were predicted upstream of genes with roles in biosynthesis and function of pili and flagella, in secretory pathways, and in cell wall biogenesis, suggesting the possible involvement of G. sulfurreducens PilR in regulation of production and assembly of pili and flagella.}, keywords = {Bacterial Proteins, Base Sequence, Binding Sites, Conserved Sequence, Ferric Compounds, Fimbriae Proteins, Gene Expression Regulation, Bacterial, Genome, Bacterial, Geobacter, Molecular Sequence Data, Promoter Regions, Genetic, Transcription Factors, Transcription, Genetic}, issn = {1879-0038}, doi = {10.1016/j.gene.2010.08.005}, author = {Krushkal, Julia and Ju{\'a}rez, Katy and Barbe, Jose F and Qu, Yanhua and Andrade, Angel and Puljic, Marko and Adkins, Ronald M and Lovley, Derek R and Ueki, Toshiyuki} } @article {473, title = {Diversity of promoter elements in a Geobacter sulfurreducens mutant adapted to disruption in electron transfer.}, journal = {Funct Integr Genomics}, volume = {9}, year = {2009}, month = {2009 Feb}, pages = {15-25}, abstract = {The delta-proteobacterium, Geobacter sulfurreducens, can obtain energy by coupling the oxidation of organic matter to the reduction of insoluble Fe(III) or the anode of a microbial fuel cell. Because Fe(III) oxide or the anode surface, in contrast to oxygen, nitrate, or sulfate, is not soluble nor can it be reduced readily, Geobacter species have developed mechanisms which allow electrons to be delivered across outer membrane to the cell surface. OmcB is an outer-membrane c-type cytochrome important for G. sulfurreducens Fe(III) respiration. In the absence of OmcB, cells lost the ability to reduce soluble or insoluble Fe(III). However, the omcB deletion mutant can slowly adapt to growth on soluble Fe(III) over prolonged incubation in the medium with acetate as the electron donor. We discuss available information about predicted or experimentally validated promoters and transcription regulatory sites identified upstream of operons with transcriptional expression significantly changed in the adapted omcB mutant. DNA sequences of upstream regions of coregulated operons in the adapted mutant are divergent, suggesting the presence of recognition sites for different transcriptional regulators and indicating that adaptation of the omcB mutant to growth on soluble Fe(III) has shifted the relevant expression networks involved to a more diverse molecular basis.}, keywords = {Adaptation, Physiological, Electron Transport, Genetic Variation, Geobacter, Mutation, Promoter Regions, Genetic}, issn = {1438-7948}, doi = {10.1007/s10142-008-0094-7}, author = {Krushkal, Julia and Leang, Ching and Barbe, Jose F and Qu, Yanhua and Yan, Bin and Puljic, Marko and Adkins, Ronald M and Lovley, Derek R} } @article {455, title = {GSEL version 2, an online genome-wide query system of operon organization and regulatory sequence elements of Geobacter sulfurreducens.}, journal = {OMICS}, volume = {13}, year = {2009}, month = {2009 Oct}, pages = {439-49}, abstract = {Geobacter sulfurreducens is a model organism within the delta-Proteobacterial family Geobacteraceae, members of which can participate in environmental bioremediation of metal and organic waste contaminants and in production of bioenergy. In this report, we describe a new, significantly expanded and updated, version 2 of the GSEL (Geobacter Sequence Elements) database ( http://geobacter.org/research/gsel2/ and http://geobacter.org/refs/gsel2/ ) and its accompanying online query system, which compiles information on operon organization and regulatory sequence elements in the genome of G. sulfurreducens. It incorporates a new online graphical browser, provides novel search capabilities, and includes updated operon predictions along with new information on predicted and experimentally validated genome regulatory sites. The GSEL database and online search system provides a unique and comprehensive tool cataloging information about gene regulation in G. sulfurreducens, aiding in investigation of mechanisms that regulate its ability to generate electric power, bioremediate environmental waste, and adapt to environmental changes.}, keywords = {Base Sequence, Databases, Genetic, Gene Expression Regulation, Bacterial, Genome, Bacterial, Geobacter, Humans, Internet, Online Systems, Operon, Regulatory Sequences, Nucleic Acid, Software, User-Computer Interface}, issn = {1557-8100}, doi = {10.1089/omi.2009.0081}, author = {Qu, Yanhua and Brown, Peter and Barbe, Jose F and Puljic, Marko and Merino, Enrique and Adkins, Ronald M and Lovley, Derek R and Krushkal, Julia} }