Kinetics of accumulation of a photodynamically induced cell-surface polypeptide in a species of Arthrobacter

Abstract

Cells of a species of Arthrobacter were incubated in the light with methylene blue, a dye that sensitizes photooxidative reactions by the production of singlet oxygen. An early and major response by the cells to these conditions was stimulation of synthesis of a single cell-surface polypeptide, 21,000 daltons in mass. The rate of synthesis of this polypeptide reached a maximal level about 30 min after the start of illumination. As a consequence, the amount of this polypeptide increased at least 10-fold during a period of 5 h. The presence of histidine or methionine, scavengers of singlet oxygen, markedly diminished synthesis and accumulation of this polypeptide. Concomitant with the accumulation of this polypeptide on the cell surface was the appearance of an extensive array of pili.containing 1 mM Na2HPO4, 0.2 mM KH2PO4, 1 mM (NH4)2SO4, 1 mM MgCl2, and 0.03 mM CaCl2. Finally, the celLs were suspended in the deficient medium 359 on July 16, 2020 by guest

Molecular cloning of a light-inducible gene (lipA) encoding a novel pilin from Arthrobacter photogonimos

“…A. photogonimos (ATCC 49663) was characterized previously [1,4]. Cultures were treated overnight at 25³C with 1 WM neutral red and 15 W m 3P white £uorescent light and then LIP was washed from cells with 3 M NaCl containing 10 mM NaHCO Q (10 ml per ml packed cells).…”

SIMILARITIES IN THE INDUCTION OF SYNTHESIS OF A CELL‐SURFACE POLYPEPTIDE IN Arthrobacter sp. BY NEAR‐UV IRRADIATION and PHOTODYNAMIC CONDITIONS

“…Cells. The characteristics of the species of Arfhrobacfer used in these experiments were described before (Hoober, 1978). The cells were grown at 25"Cin the dark, collected by centrifugation and suspended in a defined medium containing 5 mM sodium glutamate (Hoober.…”

“…Assay for induction with dyes in visible light. Cell suspensions (2-me portions in 50-rnl Erlenmeyer flasks) were exposed to cool-white fluorescent light at an incident intensity of 15 Wm-' as described before (Hoober, 1978). Dyes were added to the suspension at the time of exposure to light.…”

“…After 30 min of illumination. a time sufficient to achieve the maximal rate of synthesis of the 21 kd polypeptide (Hoober. 1978), the cells were labeled, unless stated otherwise, for an additional 30 min in the dark with a mixture of [ "C]-amino acids (1.2 pCiim6) obtained from Amersham Corporation.…”

“…Mild photodynamic conditions induce synthesis of a cell-surface polypeptide in a species of Arthrobacter ( H o o b e r , 1977, 1978). As this polypeptide accumulates, t h e cells develop an extensive array of pili, which suggests t h a t t h e polypeptide is t h e subunit of these structures (Hoober. 1978).…”