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B6db references: 99421691

type Journal Article
authors Ravina, C. G.; Barroso, C.; Vega, J. M.; Gotor, C.
title Cysteine biosynthesis in Chlamydomonas reinhardtii. Molecular cloning and regulation of O-acetylserine(thiol)lyase
journal Eur J Biochem
ui 99421691
year (1999)
volume 264
number 3
pages 848-53.
keywords Amino Acid Sequence
abstract A cDNA, Cys1ACr, encoding an isoform of O-acetylserine(thiol) lyase has been isolated from Chlamydomonas reinhardtii, using a PCR-based approach. The inclusion of dimethylsulfoxide in the PCR reaction has been demonstrated to be essential for the correct amplification of C. reinhardtii templates with complex secondary structures caused by a high G + C content. The deduced amino acid sequence exhibited highest similarity with plant O-acetylserine(thiol)lyase isoforms, indicating that the C. reinhardtii enzyme was structurally more similar to higher plant O-acetylserine(thiol)lyase than to the corresponding prokaryotic enzymes. The N-terminal extension present in Cys1ACr showed several characteristics of an organellar transit peptide, with a length typical for C. reinhardtii. Southern blot analysis suggested that the C. reinhardtii genome may contain a single copy of the organellar O- acetylserine(thiol)lyase gene. O-acetylserine(thiol)lyase activity was strongly induced by sulfur-deficient conditions (up to sevenfold the level observed in a sulfur-repleted cell culture) and required the presence of a nitrogen source. Northern blot analysis showed a different pattern of regulation of Cys1ACr to that observed at the activity level. To obtain an increase of transcript abundance a longer period of sulfur limitation was required, reaching a maximum level of approximately threefold Cys1ACr mRNA when compared with the level of a sulfate-grown culture.
last changed 2003/03/17 14:53

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