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Structure-based functional inference of hypothetical proteins from Mycoplasma hyopneumoniae.

ABSTRACT: Enzootic pneumonia caused by Mycoplasma hyopneumoniae is a major constraint to efficient pork production throughout the world. This pathogen has a small genome with 716 coding sequences, of which 418 are homologous to proteins with known functions. However, almost 42% of the 716 coding sequences are annotated as hypothetical proteins. Alternative methodologies such as threading and comparative modeling can be used to predict structures and functions of such hypothetical proteins. Often, these alternative methods can answer questions about the properties of a model system faster than experiments. In this study, we predicted the structures of seven proteins annotated as hypothetical in M. hyopneumoniae, using the structure-based approaches mentioned above. Three proteins were predicted to be involved in metabolic processes, two proteins in transcription and two proteins where no function could be assigned. However, the modeled structures of the last two proteins suggested experimental designs to identify their functions. Our findings are important in diminishing the gap between the lack of annotation of important metabolic pathways and the great number of hypothetical proteins in the M. hyopneumoniae genome.

SUBMITTER: da Fonseca MM

PROVIDER: S-EPMC3340535 | biostudies-literature | 2012 May

REPOSITORIES: biostudies-literature

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Structure-based functional inference of hypothetical proteins from Mycoplasma hyopneumoniae.

da Fonsêca Marbella Maria MM Zaha Arnaldo A Caffarena Ernesto R ER Vasconcelos Ana Tereza Ribeiro AT

Journal of molecular modeling 20110826 5

Enzootic pneumonia caused by Mycoplasma hyopneumoniae is a major constraint to efficient pork production throughout the world. This pathogen has a small genome with 716 coding sequences, of which 418 are homologous to proteins with known functions. However, almost 42% of the 716 coding sequences are annotated as hypothetical proteins. Alternative methodologies such as threading and comparative modeling can be used to predict structures and functions of such hypothetical proteins. Often, these al ...[more]

PMID: 21870198

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Project description:Mycoplasma hyopneumoniae is the causative agent of porcine enzootic pneumonia and a major factor in the porcine respiratory disease complex. A clear understanding of the mechanisms of pathogenesis does not exist although it is clear that M. hyopneumoniae adheres to porcine ciliated epithelium by action of a protein called P97. Previous studies have shown variation in the gene encoding the P97cilium adhesin within different strains of M. hyopneumoniae, but the extent of genetic variation among field strains across the genome is not known. Since M. hyopneumoniae is a worldwide problem, it is reasonable to expect that a wide range of genetic variability may exist given all of the different breed and housing conditions. This variation may impact the overall virulence of a single strain. Using microarray technology, this study examined potential variation of fourteen field strains in comparison to strain 232 on which the array was based. Genomic DNA was obtained, amplified with TempliPhiâ¢, and labeled indirectly with Alexa dyes. Post genomic hybridization, the arrays were scanned and data analyzed using a linear statistical model. Results indicate that genetic variation could be detected in all fourteen field strains but across different loci, suggesting that variation occurs throughout the genome. Fifty-nine percent of the variable loci were hypothetical genes. Twenty-two percent of the lipoprotein genes showed variation in at least one field strain. A permutation test identified a location in M. hyopneumoniae genome where spatial clustering of variability between the field strains and strain 232 exists. TempliPhiâ¢ amplified DNA samples from field isolates were compared to control strain 232 using a two-color experimental microarray design. Independent samples from one isolate labeled with one dye were paired with control samples labeled with the alternate dye; the samples were mixed and hybridized to the microarray. For nine of the fourteen isolates (95MP1501, 95MP1502, 95MP1503, 95MP1504, 95MP1508, 95MP1509, 97MP0001, 00MP1301, and 05MP2301), four independent field isolate DNA samples were paired with four independent DNA samples from control 232. In two of the four arrays, the control sample was labeled with Alexa 555 dye and compared to the field isolate sample labeled with Alexa 647 dye (Molecular Probes, Inc., Eugene, Ore.). The dye assignment to control and treated samples was reversed for the other two arrays (dye swap). The arrays were hybridized under identical conditions as described below. This procedure was repeated for isolates 95MP1510 for a total of four arrays, where the control sample was labeled with Alexa 647 dye in three of the arrays and Alexa 555 dye for the fourth array. For isolates 95MP1505, 95MP1506 and 95MP1507, a total of five arrays each, including two dye swaps, were done; and for isolate 00MP1502, a total of six arrays were done with the control labeled with Alexa 555 dye for four of the arrays and Alexa 647 for the other two arrays.

Project description:Mycoplasma hyopneumoniae (M. hyopneumoniae) is the causative agent of pandemic pneumonia among pigs, namely, swine enzootic pneumonia. Although M. hyopneumoniae was first identified in 1965, little is known regarding its metabolic pathways, which might play a pivotal role during disease pathogenesis. Lipoate is an essential cofactor for enzymes important for central metabolism. However, the lipoate metabolism pathway in M. hyopneumoniae is definitely unclear. Here, we identified a novel gene, lpl, encoding a lipoate protein ligase in the genome of M. hyopneumoniae (Mhp-Lpl). This gene contains 1,032 base pairs and encodes a protein of 343 amino acids, which is between 7.5 and 36.09% identical to lipoate protein ligases (Lpls) of other species. Similar to its homologs in other species, Mhp-Lpl catalyzes the ATP-dependent activation of lipoate to lipoyl-AMP and the transfer of the activated lipoyl onto the lipoyl domains of M. hyopneumoniae GcvH (Mhp H) in vitro. Enzymatic and mutagenesis analysis indicate that residue K56 within the SKT sequence of Mhp H protein is the lipoyl moiety acceptor site. The three-dimensional structure showed typical lipoate protein ligase folding, with a large N-terminal domain and a small C-terminal domain. The large N-terminal domain is responsible for the full enzymatic activity of Mhp-Lpl. The identification and characterization of Mhp-Lpl will be beneficial to our understanding of M. hyopneumoniae metabolism. Summary:Lipoic acid is an essential cofactor for the activation of some enzyme complexes involved in key metabolic processes. Lipoate protein ligases (Lpls) are responsible for the metabolism of lipoic acid. To date, little is known regarding the Lpls in M. hyopneumoniae. In this study, we identified a lipoate protein ligase of M. hyopneumoniae. We further analyzed the function, overall structure and ligand-binding site of this protein. The lipoate acceptor site on M. hyopneumoniae GcvH was also identified. Together, these findings reveal that Lpl exists in M. hyopneumoniae and will provide a basis for further exploration of the pathway of lipoic acid metabolism in M. hyopneumoniae.

Dataset Information

Structure-based functional inference of hypothetical proteins from Mycoplasma hyopneumoniae.

Publications

Structure-based functional inference of hypothetical proteins from Mycoplasma hyopneumoniae.

Similar Datasets

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