A novel homologue of the prokaryotic htrA gene is differentially expressed in the alga Haematococcus pluvialis following stress.
The alga Haematococcus pluvialis is able to respond to environmental stress by changing from the motile, vegetative green cell form to red stationary aplanospores. This differentiation program is accompanied by dramatic morphological changes that must result, at least in part, from differential gene expression. To begin to identify genes that are differentially expressed as a response to stress, we applied the differential display technique to identify and isolate differentially expressed RNA sequences. Here we report on the isolation and characterization of one such RNA sequence that codes for Haematococcus htrA, a member of a heat shock serine protease family previously described only in prokaryotes. Interestingly, database searches of mouse and human cDNA sequences showed that a previously unreported homologue is also found in a number of tissues. htrA mRNA was not detectable in vegetative cells, but was found at high levels in developing aplanospores. Evidence presented suggests that RNA transcripts encoding this protein are differentially spliced, and that the different splice products are differentially expressed during the developmental process. These experiments provide the groundwork upon which the developmental program of H. pluvialis can be investigated. In addition, they indicate that the htrA family of heat shock serine proteases may play an important role in stress response in higher organisms as well as in bacteria.
Hershkovits
G
G
Department of Life Sciences, Bar Ilan University, Ramat Gan, Israel.
Dubinsky
Z
Z
Katcoff
D J
DJ
D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D000460:Chlorophyta / Q000737:chemistry / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000302:isolation & purification; D004591:Electrophoresis, Polyacrylamide Gel; D005786:Gene Expression Regulation; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D033903:Periplasmic Proteins; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000737:chemistry / Q000235:genetics*; D014158:Transcription, Genetic
D018076:DNA, Complementary; D006360:Heat-Shock Proteins; D033903:Periplasmic Proteins; D012333:RNA, Messenger; C061682:DegP protease; D012697:Serine Endopeptidases