Light-induced DELTApH and DELTApsi in halobacterial vesicles related to sodium transport

Technical Report · Wed Jan 01 00:00:00 EST 1986

OSTI ID:6999731

Kamo, N; Racanclli, T; Packer, L

Membranes of Halobacterium halobium contain two retinoproteins, baceteriorhodopsin (BR/sub 568nm/) and halorhodopsin (HR/sub 588nm/). We have investigated the light- and sodium-dependent activities in vesicles from the HR containing R/sub 1/mR strain, and the BR + HR containing S/sub 9/ strain to study energy conversion and ion flow mechanisms. Simultaneous ..delta..pH and ..delta..psi measurements have been made with electrodes. In R/sub 1/mR vesicles, -..delta..psi and H/sup +/ uptake occurs in NaCl but not in KCl medium. In S/sub 9/ vesicles, net H/sup +/ extrusion is reduced at high light intensity in NaCl but not KCl medium. Such results indicate Na/sup +//H/sup +/ exchange in vesicles from both strains. As S/sub 9/ contains BR + HR, it is unclear whether the Na/sup +/ extrusion is due to a Na/sup +//H/sup +/ antiporter and/or HR which has been proposed to be a light driven Na/sup +/ pump. To evaluate these concepts for Na/sup +/ transport, the light intensity dependence and action of several membrane transport active agents have been compared. Digitoxin, electro-neutral exchangers (triphenyltin and monensin), and phloretin yielded similar results for HR (R/sub 1/mR) and HR + BR (S/sub 9/) vesicles. Moreover treatment of vesicles with carboxyl reacting reagents inhibited Na/sup +/ dependent activity in both types of vesicles. Thus, common mechanisms of Na/sup +/ transport are indicated in S/sub 9/ and R/sub 1/mR vesicles. 22 refs., 9 figs., 1 tab.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6999731
• Report Number(s): DOE/SF/00098-T10; ON: DE87003013
• Resource Relation: Other Information: Paper copy only, copy does not permit microfiche production
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
MEMBRANE TRANSPORT
PH VALUE
SODIUM CHLORIDES
BACTERIA
ELECTROPHYSIOLOGY
LIPOSOMES
MEMBRANE PORES
RHODOPSIN
ALKALI METAL COMPOUNDS
CELL CONSTITUENTS
CHLORIDES
CHLORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
MICROORGANISMS
ORGANIC COMPOUNDS
ORGANOIDS
PHYSIOLOGY
PIGMENTS
PROTEINS
SODIUM COMPOUNDS
550500* - Metabolism
550700 - Microbiology