Novel gene mutation and clinical features in a family with gyrate atrophy of choroid and retina / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To investigate the pathogenic mutations of the <i>OAT</i> gene in a Chinese family affected with gyrate atrophy of choroid and retina(GA)and describe their clinical manifestations.METHODS: All available family members have underwent detailed ophthalmological examinations. The sequencing results and pathogenic mutations were clarified by whole exome sequencing, bioinformatics analysis and Sanger sequencing.RESULTS: Based on the clinical manifestations and symptoms, the proband was diagnosed with GA. A missense mutation of c.722C>T(p.P241L)in exon 6 and a nonsense mutation of c.1186C>T(p.R396X)in exon 10 were identified in the <i>OAT</i> gene of the proband, which was a compound heterozygotic mutation. This compound heterozygous mutation showed co-segregation in the family. The heterozygous pathogenic variant of p.R396X was detected in both the proband's father and elder brother, and the heterozygous pathogenic variant of p.P241L was detected in proband's mother. Except for the proband, no other family members have abnormal clinical manifestations.CONCLUSION: The proband of this family is a compound heterozygous mutation, in which p.P241L is the first reported gene mutation type. This result expands the range of <i>OAT</i> gene variation and is conducive to further understanding the pathogenic factors of GA at the molecular basis level. The discovery and confirmation of the novel mutation type will also help to provide a new basis for the clinical diagnosis and gene therapy of GA.

A variant of ornithine aminotransferase from mouse small intestine

The ornithine aminotransferase (OAT) activity of mouse was found to be highest in the small intestine. The mitochondrial OAT from mouse small intestine was purified to homogeneity by the procedures including heart treatment, ammonium sulfate fractionation, octyl-Sepharose chromatography, and Sephadex G-150 gel filtration. Comparing to the amino acid sequence of mouse hepatic OAT, six N-terminal amino acid residues have been deleted in intestinal OAT. However, the subsequent sequence was identical with that of hepatic OAT. The molecular weights of both intestinal and hepatic OAT were estimated as 46 kDa by SDS-gel electrophoresis and as 92 kDa by gel filtration, indicating that both native OATs are dimeric. Biochemical properties of intestinal OAT, such as molecular weight, pH optimum and K(m) values for L-ornithine and alpha-ketoglutarate, were similar to those of hepatic OAT. However, intestinal OAT was more labile than hepatic OAT to tryptic digestion.

Acquiring and analyzing of ornithine aminotransferase gene of Schistosoma japonicum / 中国血吸虫病防治杂志

Objective To screen and identify the novel genes from the adult worm cDNA library of Schistosoma japonicum by the expressed sequence tags (EST) strategy.Methods The cDNA clones were selected randomly and the ESTs were obtained.The novel gene was searched for homologue identity with NCBI blast programmer.The homologue of the two sequences with a high identity was compared at amino acid and nucleotide level with the BLAST programmer,and the analysis of protein was carried out with the pcgene software. Results There was a novel gene of Schistosoma japonicum which included 1 677 bp coding for 424 amino acid residues, and it was given the accession number of sequence in Genbank(AY336497).The cDNA sequence was homologous to the known ornithine aminotransferase gene of Xenopus laevis. The identity of amino acid sequence was 66%. The academic pI was 8.52, and the antigen determinant was probably from 795 to 846 on the cDNA sequence. Conclusion EST strategy is an effective measure to discover new genes of Schistosoma japonicum. The novel gene is homologous to the ornithine aminotransferase gene of Xenopus laevis.This study is helpful to further sequential and functional search of the gene.[

Water stress induced alterations in ornithine aminotransferase of ragi (Eleusine coracana): Protection by proline against heat inactivation and denaturation by urea and guanidinium chloride.

Water stress resulted in a specific response leading to a large and significant increase (80-fold) in free proline content of ragi (Eleusine coracana) leaves and seedlings. L-Proline protected ornithine aminotransferase, an enzyme in the pathway for proline biosynthesis, isolated from normal and stressed ragi leaves against heat inactivation and denaturation by urea and guanidinium chloride. The protection of the stressed enzyme by L-proline was much more complete than that of the enzyme isolated from normal leaves. While L-ornithine, one of the substrates, protected the stressed enzyme against inactivation, it enhanced the rate of inactivation of the normal enzyme. α-Ketoglutarate protected both the normal and stressed enzyme against inactivation and denaturation. These results support the suggestion that ornithine aminotransferase has undergone a structural alteration during water stress. In view of the causal relationship between elevated temperature and water stress of plants under natural conditions, the protection afforded by proline against inactivation and denaturation of the enzyme from stressed leaves assumes significance. These results provide an explanation for a possible functional importance of proline accumulation during water stress.

Alterations in the activities of the enzymes of proline metabolism in Ragi (Eleusine coracana) leaves during water stress.

Free proline content in Ragi (Eleusine coracana) leaves increased markedly (6 to 85 fold) as the degree of water stress, created by polyethylene gylcol treatment, was prolonged There was also a marginal increase in soluble proteins in the stressed leaves as compared to that in the controls. Water stress stimulated the activities of ornithine aminotransferase and pyrroline-5-carboxylate reductase, the enzymes of proline biosynthesis and markedly inhibited the enzymes involved in proline degradation viz., proline oxidase and pyrroline-5-carboxylate dehydrogenase. These results suggest that increase in free proline content of Ragi leaves could be due to enhanced activities of the enzymes synthesizing proline but more importantly due to severe inhibition of the enzymes degrading proline. These observations establish for the first time, the pathway of proline metabolism in plants by way of detection of the activities of all the enzymes involved and also highlight the role of these enzymes in proline accumulation during water stress.