The “additional subunit” CFOII of the photosynthetic atp-synthase and the thylakoid polypeptide, binding ferredoxin nadp reductase: Are they different?

Abstract

Evidence is presented to support the notion that the 16k Dathylakoid poly peptide, called CF0II, is an essential sub unit of the photo synthetic ATP-synthase complex CF0CF1: It is co-isolated with the other sub units of CF0CF1, in preparations either using octylgluco-side/cholate or Triton X-100. It is co-precipitated by anti bodies together with the other CF0CF1, sub units. It is immuno chemically not related to thylakoid poly peptides of higher molecular weight nor to some thylakoid poly peptides with similar apparent molecular weight between 16 and 18 k Da : CF1Ɛ, CF0I, sub unit IV of the bbf complex, the 16.5 kDa polypeptide of the oxygen evolving complex of PS II, and the intrinsic ferredox in NADP reductase binding protein.The N-terminal amino acid sequences of CF0II and the reductase binding protein is determined by Ed man degradation and compared:The two sequence s are different and not identical to other characterized thylakoid polypeptides. Mono specific antibodies against CF0II inhibit rebinding of CF1, to EDTA treated thylakoid membranes, H+ efflux from EDTA treated membranes and cyclic photophosp horylation. Thus the addition Polypeptide CF0II qualifies for a functional sub unit of the photo synthetic ATP-synthase. © 1990, Walter de Gruyter. All rights reserved.