This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Kosakowski, M. H. Articles by Kaplan, S. Search for Related Content PubMed PubMed Citation Articles by Kosakowski, M. H. Articles by Kaplan, S.

 Previous Article  |  Next Article 

J Bacteriol. 1974 June; 118(3): 1144-1157
Copyright © 1974 American Society for Microbiology. All Rights Reserved.

Topology and Growth of the Intracytoplasmic Membrane System of Rhodopseudomonas spheroides: Protein, Chlorophyll, and Phospholipid Insertion into Steady-State Anaerobic Cells

^a Department of Microbiology, University of Illinois, Urbana, Illinois 61801

ABSTRACT

An equilibrium density gradient centrifugation study involving the separation of "old" and "new" membranes has been developed to determine the manner in which protein, lipid, and chlorophyll are incorporated into growing intracytoplasmic membranes (chromatophores) of Rhodopseudomonas spheroides. Chromatophores derived from cells grown in an H₂O-medium had a density of 1.175 to 1.180 g/cm³ and were readily separable from chromatophores having a density of 1.220 to 1.230 isolated from cells grown in a 70% D₂O-medium. After a shift from "D₂O-" to "H₂O"-based media, only hybrid chromatophores derived from a combination of "heavy" (old) and "light" (new) chromatophore material could be detected. The experimentally determined, median density values for the growing intracytoplasmic membrane system followed a theoretically determined profile which was calculated from the density of full "heavy" and full "light" material assuming random, homogeneous incorporation of new material into old membrane. The distribution of the radioactive labels for protein (leucine) and chlorophyll (delta-aminolevulinic acid) were identical and showed a reproducible displacement of the "old" material to the heavy side of the optical density at 365 nm (OD₃₆₅) absorbance and a displacement of the "new" material to the light side of the OD₃₆₅ absorbance profile. Specific phospholipid growth showed no displacement for either the "old" or "new" material from the median absorbance profile.

¹ Present address: Fachbereich für Biologie der Universität Regensburg, 84 Regensburg, Germany.