Rhesus expression in a green alga is regulated by CO(2).
The function of the Rhesus (Rh) complex in the human red cell membrane has been unknown for six decades. Based on the organismal, organ, and tissue distribution of Rh proteins, and on our evidence that their only known paralogues, the ammonium and methylammonium transport proteins (also called methylammonium permeases), are gas channels for NH(3), we recently speculated that Rh proteins are biological gas channels for CO(2). Like NH(3), CO(2) differs from other gases in being readily hydrated. We have now tested our speculation by studying expression of the RH1 gene in the photosynthetic microbe Chlamydomonas reinhardtii. Expression of RH1 was high for cells grown in air supplemented with 3% CO(2) or shifted from air to high CO(2) (3%) for 3 h. Conversely, RH1 expression was low for cells grown in air (0.035% CO(2)) or shifted from high CO(2) to air for 3 h. These results make viable the hypothesis that Rh1 and Rh proteins generally are gas channels for CO(2).
Soupene
Eric
E
Department of Plant and Microbial Biology, University of California, 111 Koshland Hall, Berkeley, CA 94720-3102, USA.
King
Natalie
N
Feild
Eithne
E
Liu
Phillip
P
Niyogi
Krishna K
KK
Huang
Cheng-Han
CH
Kustu
Sydney
S
D000595:Amino Acid Sequence; D000818:Animals; D002245:Carbon Dioxide / Q000494:pharmacology*; D016825:Chlamydomonas reinhardtii / Q000187:drug effects / Q000502:physiology*; D003001:Cloning, Molecular; D018076:DNA, Complementary; D005786:Gene Expression Regulation / Q000187:drug effects*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics; D012204:Rh-Hr Blood-Group System / Q000235:genetics*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
D018076:DNA, Complementary; D012333:RNA, Messenger; D012204:Rh-Hr Blood-Group System; D002245:Carbon Dioxide