This entry includes the CDP-archaeol synthase from archaea and a group of putative integral membrane proteins from bacteria. CDP-archaeol synthase functions in the archaeal lipid biosynthetic pathway. It catalyses the transfer of the nucleotide to its specific archaeal lipid substrate, leading to the formation of a CDP-activated precursor (CDP-archaeol) to which polar head groups are attached [].
CarS, an antirepressor present in Cystobacterineae, recognizes repressors to turn on the photo-inducible promoter P(B). In the dark, access to the P(B) promoter is blocked by the repressor CarA []. Blue light causes expression of CarS, leading the way to the CarA-CarS interaction which dismantles the CarA-operator complex, resulting in the derepression of the P(B) promoter [, ]. A parallel pathway for regulating P(B) involves the interaction of CarS with the repressor CarH, which shares the domain architecture of CarA. CarH and CarA contain an N-terminal, MerR-type winged-helix DNA-binding domain that recognizes CarS. CarS adopts an SH3-like fold with loop length variations and acts as an operator DNA mimic [].
This is an SH3 domain found in antirepressor proteins such as CarS from Myxococcus xanthus. CarS antirepressor recognizes and neutralizes its cognate repressors to turn on a photo-inducible promoter. CarS physically interacts with the MerR-type winged-helix DNA-binding domain of these repressors leading to activation of carB operon. Structural studies of CarS from M. Xanthus reveals a β-barrel fold akin to that in SH3 domains. However, it diverges from the typical SH3 domain fold in the lengths and conformations of the connecting loops. Functional analysis reveal that SH3 domain-like fold in the antirepressor CasS, mimics operator DNA in sequestering the repressor DNA recognition helix to activate transcription [].
CarS (CDP-archaeol synthase) is a membrane protein that functions in the archaeal lipid biosynthetic pathway. It catalyses the transfer of the nucleotide to its specific archaeal lipid substrate, leading to the formation of a CDP-activated precursor (CDP-archaeol) to which polar head groups are attached [].
This entry includes C2-domain abscisic acid-related protein CAR1-11 from Arabidopsis and GTPase activating protein 1 (OsGAP1) from rice. CARs interact with the PYR/PYL ABA receptors and recruit them to membranes in a Ca2+-dependent manner []. OsGAP1 is a soluble protein that can loosely associate with plasma membrane. It can also interact with an unconventional G-protein, OsYchF1, and stimulate its NTPase activities [].
