Research note: Characterization of a cDNA encoding glutamine synthetase II from Gelidium crinale (Rhodophyta)

Abstract

SUMMARY A cDNA encoding glutamine synthetase (GS) was characterized from the red alga, Gelidium crinale (Turner) Gaillon, using reverse-transcriptase polymerase chain reaction and the 5′- and 3′-rapid amplification of cDNA ends. Sequence analysis of a 1231-bp GS cDNA transcript included both 5′ and 3′ untranslated regions and a 1056-bp open reading frame encoding a 352 amino acid polypeptide. Comparison with GS sequences from other organisms revealed that the G. crinale cDNA encodes a type-II GS, and the absence of a N-terminal plastid signal sequence suggests that it is a cytosolic isoenzyme. Phylogenetic analyses of GSII amino acid sequences supports the multiple origin of cytosolic and plastid isoenzymes during eukaryotic evolution.