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K Suvarna

Publications and source records attributed to K Suvarna.

8 recordsLinked to original sources
PubMed2006

A novel amyloidogenic transthyretin variant, Gly53Ala, associated with intermittent headaches and ataxia.

We report a novel transthyretin variant, Gly53Ala, in a 44-year-old British woman who presented with severe episodic headaches, often with focal neurological deficit, before developing progressive ataxia, depression, dementia and eventually peripheral neuropathy. Transthyretin amyloidosis was confirmed on biopsy of the heart muscle. Serum amyloid P component scintigraphy did not show visceral amyloid in extra-cardiac sites, but magnetic resonance imaging indicated diffuse leptomeningeal amyloidosis.

Adult↗
PubMed2005

Case report: pulmonary blastoma: presentation of two atypical cases and review of the literature.

Pulmonary blastoma is a relatively rare aggressive adult malignancy. The clinical and radiographic features of two cases are described and the literature reviewed. Pulmonary blastoma usually presents radiologically as a well-defined mass lesion on chest radiography, which may be large enough to completely opacify the hemithorax and cause mediastinal shift. On CT, pulmonary blastoma is seen as a mixed solid and cystic lesion with variable contrast enhancement and a necrotic centre. Pleural effusion may be present but is not the predominant abnormality. Our cases are unusual as recurrent pleural effusions in the absence of a significant lung mass were the presenting findings.

Adult↗
PubMed1998

Molecular analysis of the LYS2 gene of Candida albicans: homology to peptide antibiotic synthetases and the regulation of the alpha-aminoadipate reductase.

The unique alpha-aminoadipate pathway for lysine biosynthesis is present only in fungi and involves eight enzyme steps. alpha-Aminoadipate semialdehyde dehydrogenase, commonly called alpha-aminoadipate reductase (AAR), catalyzes the conversion of alpha-aminoadipic acid to alpha-aminoadipic semialdehyde by a novel mechanism. Two genes, LYS2 and LYS5, encode the heterodimeric enzyme in Saccharomyces cerevisiae. The LYS2 gene of Candida albicans was shown to be contained in the 4.8-kb insert of the plasmid pCaLYS2. This plasmid complemented lys2 mutants of both S. cerevisiae and C. albicans. The S. cerevisiae and C. albicans Lys2(+) transformants exhibited 138% and 160% of wild-type AAR activity, respectively. The DNA-sequence analysis of the 4.8-kb region in plasmid pCaLYS2 and a PCR product from genomic DNA which overlapped with the 4.8-kb insert revealed a continuous ORF of 4173 nucleotides encoding 1391 amino-acid residues. The C. albicans LYS2 ORF exhibited 63.0% identity at the nucleotide level and 56.2% identity at the amino-acid level to the LYS2 gene of S. cerevisiae. The ORF is preceded by consensus sequences for the TATA-, CAAT- and GCN4-box elements. An S. cerevesiae-type transcription termination signal is seen in the 3' flanking region. The deduced amino-acid sequence revealed a motif for an AMP-binding site and also the highly conserved core sequences common to peptide antibiotic synthetases. The LYS2 mRNA and alpha-aminoadipate reductase activity were repressed to a higher level in YEPD-grown cells than in cells grown in the presence of lysine or minimal medium. Additionally, AAR was shown to be feedback-inhibited by lysine and the lysine analog, thialysine. The results of the present report reveal the molecular characteristics of the LYS2 gene of C. albicans, its homology to peptide antibiotic synthetases, its divergence from the LYS2 gene of S. cerevisiae, and the regulation of AAR in C. albicans.

Aldehyde Oxidoreductases↗
PubMed1998

Menaquinone (vitamin K2) biosynthesis: localization and characterization of the menA gene from Escherichia coli.

A key reaction in the biosynthesis of menaquinone involves the conversion of the soluble bicyclic naphthalenoid compound 1, 4-dihydroxy-2-naphthoic acid (DHNA) to the membrane-bound demethylmenaquinone. The enzyme catalyzing this reaction, DHNA-octaprenyltransferase, attaches a 40-carbon side chain to DHNA. The menA gene encoding this enzyme has been cloned and localized to a 2.0-kb region of the Escherichia coli genome between cytR and glpK. DNA sequence analysis of the cloned insert revealed a 308-codon open reading frame (ORF), which by deletion analyses was shown to restore anaerobic growth of a menA mutant. Reverse-phase high-performance liquid chromatography analysis of quinones extracted from the orf-complemented cells independently confirmed the restoration of menaquinone biosynthesis, and similarly, analyses of isolated cell membranes for DHNA octaprenyltransferase activity confirmed the introduction of the menA product into the orf-complemented menA mutant. The validity of an ORF-associated putative promoter sequence was confirmed by primer extension analyses.

Alkyl and Aryl Transferases↗
PubMed1992

Menaquinone (vitamin K2) biosynthesis: nucleotide sequence and expression of the menB gene from Escherichia coli.

In Escherichia coli, the biosynthesis of the electron carrier menaquinone (vitamin K2) involves at least seven identified enzymes. One of these, naphthoate synthase, forms the bicyclic ring system by catalyzing the conversion of o-succinylbenzoyl-coenzyme A to 1,4-dihydroxy-2-naphthoic acid. The gene for this enzyme has been previously identified as menB. By genetic and biochemical tests, a 1.349-kb DNA fragment from the E. coli men locus complements menB mutants. This fragment contains a single 285-codon open reading frame (ORF). Recombinant plasmids containing deletions of either the amino or the carboxy region of the ORF fail to complement the mutants. The ORF is preceded by consensus sequences for a ribosomal binding site and a sigma 70 promoter. menB transcription sufficient to complement the menB mutant in vivo and in vitro can be initiated from the identified putative promoter, and that in the constructs, menB expression, can be made independent of read-through transcription from the lac promoter. However, multicopy plasmids containing menB fail to generate the expected levels of enzymatic activity.

Amino Acid Sequence↗