The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Patricia L Morris - One of the best experts on this subject based on the ideXlab platform.
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sumoylation regulates germinal vesicle breakdown and the akt pkb pathway during mouse oocyte maturation
American Journal of Physiology-cell Physiology, 2018Co-Authors: Weber Beringui Feitosa, Patricia L MorrisAbstract:SUMOylation, a process of Posttranslational Modification of proteins by the small ubiquitin-related modifier (SUMO) family of proteins, is known to be involved in yeast and mammalian somatic cell-c...
Christopher T Walsh - One of the best experts on this subject based on the ideXlab platform.
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Labeling proteins with small molecules by site-specific Posttranslational Modification.
Journal of the American Chemical Society, 2004Co-Authors: Xiaohua Li, Christopher T WalshAbstract:We report here the development of a general strategy for site-specific labeling of proteins with small molecules by Posttranslational Modification enzyme, phosphopantetheinyl transferase Sfp. The target proteins are expressed as fusions to the peptide carrier protein (PCP) excised from nonribosomal peptide synthetase, and Sfp catalyzes the covalent Modification of a specific serine residue on PCP by the small molecule−phosphopantetheinyl conjugate. The labeling reaction proceeds with high specificity and efficiency, targeting PCP fusion proteins in the cell lysate. The PCP tag has been shown to be compatible with various proteins, and Sfp-catalyzed PCP Modification, compatible with various small-molecule probes conjugated to coenzyme A, highlighting the potential of the PCP tag for site-specific protein labeling with small molecules.
Xiaohua Li - One of the best experts on this subject based on the ideXlab platform.
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Labeling proteins with small molecules by site-specific Posttranslational Modification.
Journal of the American Chemical Society, 2004Co-Authors: Xiaohua Li, Christopher T WalshAbstract:We report here the development of a general strategy for site-specific labeling of proteins with small molecules by Posttranslational Modification enzyme, phosphopantetheinyl transferase Sfp. The target proteins are expressed as fusions to the peptide carrier protein (PCP) excised from nonribosomal peptide synthetase, and Sfp catalyzes the covalent Modification of a specific serine residue on PCP by the small molecule−phosphopantetheinyl conjugate. The labeling reaction proceeds with high specificity and efficiency, targeting PCP fusion proteins in the cell lysate. The PCP tag has been shown to be compatible with various proteins, and Sfp-catalyzed PCP Modification, compatible with various small-molecule probes conjugated to coenzyme A, highlighting the potential of the PCP tag for site-specific protein labeling with small molecules.
Michael Ibba - One of the best experts on this subject based on the ideXlab platform.
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EF-P Posttranslational Modification Has Variable Impact on Polyproline Translation in Bacillus subtilis
mBio, 2018Co-Authors: Anne Witzky, Katherine R. Hummels, Rodney Tollerson, Andrei Rajkovic, Lisa A. Jones, Daniel B. Kearns, Michael IbbaAbstract:Elongation factor P (EF-P) is a ubiquitous translation factor that facilitates translation of polyproline motifs. In order to perform this function, EF-P generally requires Posttranslational Modification (PTM) on a conserved residue. Although the position of the Modification is highly conserved, the structure can vary widely between organisms. In Bacillus subtilis, EF-P is modified at Lys32 with a 5-aminopentanol moiety. Here, we use a forward genetic screen to identify genes involved in 5-aminopentanolylation. Tandem mass spectrometry analysis of the PTM mutant strains indicated that ynbB, gsaB, and ymfI are required for Modification and that yaaO, yfkA, and ywlG influence the level of Modification. Structural analyses also showed that EF-P can retain unique intermediate Modifications, suggesting that 5-aminopentanol is likely directly assembled on EF-P through a novel Modification pathway. Phenotypic characterization of these PTM mutants showed that each mutant does not strictly phenocopy the efp mutant, as has previously been observed in other organisms. Rather, each mutant displays phenotypic characteristics consistent with those of either the efp mutant or wild-type B. subtilis depending on the growth condition. In vivo polyproline reporter data indicate that the observed phenotypic differences result from variation in both the severity of polyproline translation defects and altered EF-P context dependence in each mutant. Together, these findings establish a new EF-P PTM pathway and also highlight a unique relationship between EF-P Modification and polyproline context dependence.IMPORTANCE Despite the high level of conservation of EF-P, the Posttranslational Modification pathway that activates EF-P is highly divergent between species. Here, we have identified and characterized in B. subtilis a novel Posttranslational Modification pathway. This pathway not only broadens the scope of potential EF-P Modification strategies, but it also indicates that EF-P Modifications can be assembled directly on EF-P. Furthermore, characterization of these PTM mutants has established that an altered Modification state can impact both the severity of polyproline translational defects and context dependence.
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EF-P Posttranslational Modification Has Variable Impact on Polyproline Translation in Bacillus subtilis
American Society for Microbiology, 2018Co-Authors: Anne Witzky, Katherine R. Hummels, Rodney Tollerson, Andrei Rajkovic, Lisa A. Jones, Daniel B. Kearns, Michael Ibba, Susan GottesmanAbstract:Elongation factor P (EF-P) is a ubiquitous translation factor that facilitates translation of polyproline motifs. In order to perform this function, EF-P generally requires Posttranslational Modification (PTM) on a conserved residue. Although the position of the Modification is highly conserved, the structure can vary widely between organisms. In Bacillus subtilis, EF-P is modified at Lys32 with a 5-aminopentanol moiety. Here, we use a forward genetic screen to identify genes involved in 5-aminopentanolylation. Tandem mass spectrometry analysis of the PTM mutant strains indicated that ynbB, gsaB, and ymfI are required for Modification and that yaaO, yfkA, and ywlG influence the level of Modification. Structural analyses also showed that EF-P can retain unique intermediate Modifications, suggesting that 5-aminopentanol is likely directly assembled on EF-P through a novel Modification pathway. Phenotypic characterization of these PTM mutants showed that each mutant does not strictly phenocopy the efp mutant, as has previously been observed in other organisms. Rather, each mutant displays phenotypic characteristics consistent with those of either the efp mutant or wild-type B. subtilis depending on the growth condition. In vivo polyproline reporter data indicate that the observed phenotypic differences result from variation in both the severity of polyproline translation defects and altered EF-P context dependence in each mutant. Together, these findings establish a new EF-P PTM pathway and also highlight a unique relationship between EF-P Modification and polyproline context dependence
Renu A Kowluru - One of the best experts on this subject based on the ideXlab platform.
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Posttranslational Modification of mitochondrial transcription factor a in impaired mitochondria biogenesis implications in diabetic retinopathy and metabolic memory phenomenon
Experimental Eye Research, 2014Co-Authors: Julia M Santos, Manish Mishra, Renu A KowluruAbstract:Mitochondrial transcription factor A (TFAM) is one of the key regulators of the transcription of mtDNA. In diabetes, despite increase in gene transcripts of TFAM, its protein levels in the mitochondria are decreased and mitochondria copy numbers become subnormal. The aim of this study is to investigate the mechanism(s) responsible for decreased mitochondrial TFAM in diabetes. Using retinal endothelial cells, we have investigated the effect of overexpression of cytosolic chaperone, Hsp70, and TFAM on glucose-induced decrease in mitochondrial TFAM levels, and the transcription of mtDNA-encoded genes, NADH dehydrogenase subunit 6 (ND6) and cytochrome b (Cytb). To investigate the role of Posttranslational Modifications in subnormal mitochondrial TFAM, ubiquitination of TFAM was assessed, and the results were confirmed in the retina from streptozotocin-induced diabetic rats. While overexpression of Hsp70 failed to prevent glucose-induced decrease in mitochondrial TFAM and transcripts of ND6 and Cytb, overexpression of TFAM ameliorated decrease in its mitochondrial protein levels and transcriptional activity. TFAM was ubiquitinated by high glucose, and PYR-41, an inhibitor of ubiquitination, prevented TFAM ubiquitination and restored the transcriptional activity. Similarly, TFAM was ubiquitinated in the retina from diabetic rats, and it continued to be modified after reinstitution of normal glycemia. Our results clearly imply that the ubiquitination of TFAM impedes its transport to the mitochondria resulting in subnormal mtDNA transcription and mitochondria dysfunction, and inhibition of ubiquitination restores mitochondrial homeostasis. Reversal of hyperglycemia does not provide any benefit to TFAM ubiquitination. Thus, strategies targeting Posttranslational Modification could provide an avenue to preserve mitochondrial homeostasis, and inhibit the development/progression of diabetic retinopathy.