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Genetic redundancy and gene fusion in the genome of the baker's yeast Saccharomyces cerevisiae : functional characterization of a three‐member gene family involved in the thiamine biosynthetic pathway
Author(s) -
Llorente Bertrand,
Fairhead Cécile,
Dujon Bernard
Publication year - 1999
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.1999.01412.x
Subject(s) - biology , gene , genetics , genome , saccharomyces cerevisiae , gene family , yeast , computational biology
Redundancy is a salient feature of all living organisms' genome. The yeast genome contains a large number of gene families of previously uncharacterized functions that can be used to explore the functional significance of structural redundancy in a systematic manner. In this work, we describe results on a three‐member gene family with moderately divergent sequences ( YOL055c , YPL258c and YPR121w ). We demonstrate that two members are isofunctional and encode a hydroxymethylpyrimidine phosphate (HMP‐P) kinase (EC 2.7.4.7), an activity required for the final steps of thiamine biosynthesis, whose genes were not previously known in yeast. In addition, we show that the three genes are each composed of two distinct domains, each corresponding to individual genes in prokaryotes, suggesting gene fusion during evolution. The function of the carboxy‐terminal part of the proteins is not yet understood, but it is not required for HMP‐P kinase activity. Expression of all three genes is regulated in the same way. Several other examples of gene fusions exist in the same biosynthetic pathway when eukaryotic genes are compared with prokaryotic ones.