Regulation of the expression of intracellular beta-carbonic anhydrase in response to CO2 and light in the marine diatom Phaeodactylum tricornutum.
Cells of the marine diatom Phaeodactylum tricornutum Bohlin (UTEX 642) grown in 5% CO(2) were transferred to air-level CO(2) in the light or dark and allowed to acclimate to air. No accumulation of the transcript of the P. tricornutum beta-carbonic anhydrase 1 (ptca1) was detected in 5% CO(2)-grown cells, but ptca1 mRNA accumulated and reached a peak after 6 h acclimation to air but decreased over the next 18 h. A similar accumulation time course was observed in cells air-acclimated in the dark, except that levels of mRNA were <50% those in the light. These results suggest that air-level [CO(2)] is required to trigger the transcription of ptca1 and that light affects the extent of acclimation. During acclimation to air for 120 h in the light, levels of ptca1 mRNA exhibited a periodic oscillation with a cycle of about 24 h, which, however, was not reflected in protein accumulation levels. A 5'-upstream region from the transcription-start site toward -1,292 bp of ptca1 was cloned by inverse polymerase chain reaction, and 5'-truncations were carried out on this fragment. The truncated promoter regions were fused with the beta-glucuronidase gene (uidA) and introduced into P. tricornutum. The promoter fragments, truncated at positions -1,292, -824, -484, -225, and -70 bp, conferred on transformants clear CO(2)-responsive beta-glucuronidase expressions. In contrast, the CO(2)-responsive regulation was severely impaired or completely abolished by truncations, respectively, at position -50 or -30 bp. These results indicate that critical cis-elements required for CO(2)-responsive transcription of ptca1 may be located between -70 and -30 bp relative to the transcription start site.
Harada
Hisashi
H
Department of Bioscience, School of Science and Technology, Kwansei-Gakuin University, Sanda, Hyogo, Japan.
Nakatsuma
Daisuke
D
Ishida
Maki
M
Matsuda
Yusuke
Y
D001483:Base Sequence; D002245:Carbon Dioxide / Q000494:pharmacology; D002256:Carbonic Anhydrases / Q000235:genetics / Q000378:metabolism*; D048028:DNA, Algal / Q000235:genetics; D017377:Diatoms / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000528:radiation effects; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000528:radiation effects; D017930:Genes, Reporter; D005966:Glucuronidase / Q000235:genetics; D007700:Kinetics; D008027:Light; D008969:Molecular Sequence Data; D048030:RNA, Algal / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
D048028:DNA, Algal; D048030:RNA, Algal; D012333:RNA, Messenger; D002245:Carbon Dioxide; D005966:Glucuronidase; D002256:Carbonic Anhydrases