scholarly journals Genetic Localization and Molecular Characterization of Two Key Genes (mitAB) Required for Biosynthesis of the Antitumor Antibiotic Mitomycin C

1999 ◽  
Vol 181 (7) ◽  
pp. 2199-2208 ◽  
Author(s):  
Yingqing Mao ◽  
Mustafa Varoglu ◽  
David H. Sherman
Keyword(s):  
Amino Acid ◽  
Mitomycin C ◽  
Site Directed Mutagenesis ◽  
Nucleotide Sequence Analysis ◽  
Resistance Locus ◽  
Antitumor Antibiotic ◽  
Carbamoyl Phosphate ◽  
Acid Protein ◽  
Key Genes ◽  
Amino Acid Protein

ABSTRACT Mitomycin C (MC) is an antitumor antibiotic derived biosynthetically from 3-amino-5-hydroxybenzoic acid (AHBA),d-glucosamine, and carbamoyl phosphate. A gene (mitA) involved in synthesis of AHBA has been identified and found to be linked to the MC resistance locus, mrd, inStreptomyces lavendulae. Nucleotide sequence analysis showed that mitA encodes a 388-amino-acid protein that has 71% identity (80% similarity) with the rifamycin AHBA synthase fromAmycolatopsis mediterranei, as well as with two additional AHBA synthases from related ansamycin antibiotic-producing microorganisms. Gene disruption and site-directed mutagenesis of theS. lavendulae chromosomal copy of mitAcompletely blocked the production of MC. The function ofmitA was confirmed by complementation of an S. lavendulae strain containing a K191A mutation in MitA with AHBA. A second gene (mitB) encoding a 272-amino-acid protein (related to a group of glycosyltransferases) was identified immediately downstream of mitA that upon disruption resulted in abrogation of MC synthesis. This work has localized a cluster of key genes that mediate assembly of the unique mitosane class of natural products.

scholarly journals Identification and Analysis of Genes Involved in Anaerobic Toluene Metabolism by Strain T1: Putative Role of a Glycine Free Radical

1998 ◽  
Vol 64 (5) ◽  
pp. 1650-1656 ◽  
Author(s):  
Peter W. Coschigano ◽  
Thomas S. Wehrman ◽  
L. Y. Young
Keyword(s):  
Free Radical ◽  
Amino Acid ◽  
Molecular Mass ◽  
Cysteine Residue ◽  
Open Reading Frames ◽  
Site Directed Mutagenesis ◽  
Pyruvate Formate Lyase ◽  
Calculated Molecular Mass ◽  
Acid Protein ◽  
Amino Acid Protein

ABSTRACT The denitrifying strain T1 is able to grow with toluene serving as its sole carbon source. Two mutants which have defects in this toluene utilization pathway have been characterized. A clone has been isolated, and subclones which contain tutD and tutE, two genes in the T1 toluene metabolic pathway, have been generated. ThetutD gene codes for an 864-amino-acid protein with a calculated molecular mass of 97,600 Da. The tutE gene codes for a 375-amino-acid protein with a calculated molecular mass of 41,300 Da. Two additional small open reading frames have been identified, but their role is not known. The TutE protein has homology to pyruvate formate-lyase activating enzymes. The TutD protein has homology to pyruvate formate-lyase enzymes, including a conserved cysteine residue at the active site and a conserved glycine residue that is activated to a free radical in this enzyme. Site-directed mutagenesis of these two conserved amino acids shows that they are also essential for the function of TutD.

scholarly journals Characterization of the Gallate Dioxygenase Gene: Three Distinct Ring Cleavage Dioxygenases Are Involved in Syringate Degradation by Sphingomonas paucimobilis SYK-6

2005 ◽  
Vol 187 (15) ◽  
pp. 5067-5074 ◽  
Author(s):  
Daisuke Kasai ◽  
Eiji Masai ◽  
Keisuke Miyauchi ◽  
Yoshihiro Katayama ◽  
Masao Fukuda
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequences ◽  
Terminal Region ◽  
Ring Cleavage ◽  
Sphingomonas Paucimobilis ◽  
Acid Protein ◽  
Demethylation Pathway ◽  
Dioxygenase Gene ◽  
Amino Acid Protein

ABSTRACT Sphingomonas paucimobilis SYK-6 converts vanillate and syringate to protocatechuate (PCA) and 3-O-methylgallate (3MGA) in reactions with the tetrahydrofolate-dependent O-demethylases LigM and DesA, respectively. PCA is further degraded via the PCA 4,5-cleavage pathway, whereas 3MGA is metabolized via three distinct pathways in which PCA 4,5-dioxygenase (LigAB), 3MGA 3,4-dioxygenase (DesZ), and 3MGA O-demethylase (LigM) are involved. In the 3MGA O-demethylation pathway, LigM converts 3MGA to gallate, and the resulting gallate appears to be degraded by a dioxygenase other than LigAB or DesZ. Here, we isolated the gallate dioxygenase gene, desB, which encodes a 418-amino-acid protein with a molecular mass of 46,843 Da. The amino acid sequences of the N-terminal region (residues 1 to 285) and the C-terminal region (residues 286 to 418) of DesB exhibited ca. 40% and 27% identity with the sequences of the PCA 4,5-dioxygenase β and α subunits, respectively. DesB produced in Escherichia coli was purified and was estimated to be a homodimer (86 kDa). DesB specifically attacked gallate to generate 4-oxalomesaconate as the reaction product. The Km for gallate and the V max were determined to be 66.9 ± 9.3 μM and 42.7 ± 2.4 U/mg, respectively. On the basis of the analysis of various SYK-6 mutants lacking the genes involved in syringate degradation, we concluded that (i) all of the three-ring cleavage dioxygenases are involved in syringate catabolism, (ii) the pathway involving LigM and DesB plays an especially important role in the growth of SYK-6 on syringate, and (iii) DesB and LigAB are involved in gallate degradation.

scholarly journals LASS3 (longevity assurance homologue 3) is a mainly testis-specific (dihydro)ceramide synthase with relatively broad substrate specificity

2006 ◽  
Vol 398 (3) ◽  
pp. 531-538 ◽  
Author(s):  
Yukiko Mizutani ◽  
Akio Kihara ◽  
Yasuyuki Igarashi
Keyword(s):  
Amino Acid ◽  
Substrate Specificity ◽  
Family Members ◽  
Fatty Acyl ◽  
Ceramide Synthase ◽  
Broad Substrate Specificity ◽  
Acid Protein ◽  
Amino Acid Protein

The LASS (longevity assurance homologue) family members are highly conserved from yeasts to mammals. Five mouse and human LASS family members, namely LASS1, LASS2, LASS4, LASS5 and LASS6, have been identified and characterized. In the present study we cloned two transcriptional variants of hitherto-uncharacterized mouse LASS3 cDNA, which encode a 384-amino-acid protein (LASS3) and a 419-amino-acid protein (LASS3-long). In vivo, [3H]dihydrosphingosine labelling and electrospray-ionization MS revealed that overproduction of either LASS3 isoform results in increases in several ceramide species, with some preference toward those having middle- to long-chain-fatty acyl-CoAs. A similar substrate preference was observed in an in vitro (dihydro)ceramide synthase assay. These results indicate that LASS3 possesses (dihydro)ceramide synthesis activity with relatively broad substrate specificity. We also found that, except for a weak display in skin, LASS3 mRNA expression is limited almost solely to testis, implying that LASS3 plays an important role in this gland.

glsA, a Volvox gene required for asymmetric division and germ cell specification, encodes a chaperone-like protein

Development ◽  
1999 ◽  
Vol 126 (4) ◽  
pp. 649-658 ◽  
Author(s):  
S.M. Miller ◽  
D.L. Kirk
Keyword(s):  
Mitotic Spindle ◽  
Site Directed Mutagenesis ◽  
Cell Specification ◽  
Division Plane ◽  
Binding Domains ◽  
Acid Protein ◽  
Germ Cell Specification ◽  
Asymmetric Divisions ◽  
Dividing Cells ◽  
Amino Acid Protein

The gls genes of Volvox are required for the asymmetric divisions that set apart cells of the germ and somatic lineages during embryogenesis. Here we used transposon tagging to clone glsA, and then showed that it is expressed maximally in asymmetrically dividing embryos, and that it encodes a 748-amino acid protein with two potential protein-binding domains. Site-directed mutagenesis of one of these, the J domain (by which Hsp40-class chaperones bind to and activate specific Hsp70 partners) abolishes the capacity of glsA to rescue mutants. Based on this and other considerations, including the fact that the GlsA protein is associated with the mitotic spindle, we discuss how it might function, in conjunction with an Hsp70-type partner, to shift the division plane in asymmetrically dividing cells.

scholarly journals The Vicious Circle of Hepatic Glucagon Resistance in Non-Alcoholic Fatty Liver Disease

2020 ◽  
Vol 9 (12) ◽  
pp. 4049
Author(s):  
Katrine D. Galsgaard
Keyword(s):  
Liver Disease ◽  
Amino Acid ◽  
Fatty Liver ◽  
Protein Metabolism ◽  
Fatty Liver Disease ◽  
Plasma Concentrations ◽  
Alcoholic Fatty Liver ◽  
Acid Protein ◽  
Alcoholic Fatty Liver Disease ◽  
Amino Acid Protein

A key criterion for the most common chronic liver disease—non-alcoholic fatty liver disease (NAFLD)—is an intrahepatic fat content above 5% in individuals who are not using steatogenic agents or having significant alcohol intake. Subjects with NAFLD have increased plasma concentrations of glucagon, and emerging evidence indicates that subjects with NAFLD may show hepatic glucagon resistance. For many years, glucagon has been thought of as the counterregulatory hormone to insulin with a primary function of increasing blood glucose concentrations and protecting against hypoglycemia. However, in recent years, glucagon has re-emerged as an important regulator of other metabolic processes including lipid and amino acid/protein metabolism. This review discusses the evidence that in NAFLD, hepatic glucagon resistance may result in a dysregulated lipid and amino acid/protein metabolism, leading to excess accumulation of fat, hyperglucagonemia, and increased oxidative stress contributing to the worsening/progression of NAFLD.

scholarly journals Identification and expression of Pen c 2, a novel allergen from Penicillium citrinum

1999 ◽  
Vol 341 (1) ◽  
pp. 51-59 ◽  
Author(s):  
Lu-Ping CHOW ◽  
Ning-Yuan SU ◽  
Chia-Jung YU ◽  
Bor-Luen CHIANG ◽  
Horng-Der SHEN
Keyword(s):  
Amino Acid ◽  
Serine Proteases ◽  
Catalytic Triad ◽  
Penicillium Citrinum ◽  
E Coli ◽  
Acid Protein ◽  
Amino Acid Signal Peptide ◽  
Cloned Cdna ◽  
Allergic Disorders ◽  
Amino Acid Protein

The mould genus, Penicillium, is known to be a significant source of environmental aero-allergens. One important allergen from Penicillium citrinum, Pen c 2, has been identified by means of two-dimensional immunoblotting using IgE-containing patients' sera. This novel allergen was cloned, sequenced and expressed in Escherichia coli. The cloned cDNA encodes a large 457-amino acid protein precursor containing a 16-amino acid signal peptide, a 120-amino acid propeptide and the 321-amino acid mature protein. Comparison of the Pen c 2 sequence with known protein sequences revealed shared high sequence similarities with two vacuolar serine proteases from Aspergillus niger and Saccharomyces cerevisiae. Asp-46, His-78 and Ser-244 were found to constitute the catalytic triad of the 39-kDa Pen c 2. The DNA coding for Pen c 2 was cloned into vector PQE-30 and expressed in E. coli as a His-tag fusion protein that bound serum IgE from Penicillium-allergic patients on immunoblots. Recombinant Pen c 2 could therefore be used effectively for diagnosis and also potentially for the treatment of mould-derived allergic disorders.

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