Macroscopic phototactic behavior of the purple photosynthetic bacterium Rhodospirillum centenum

1995 ◽  
Vol 163 (1) ◽  
pp. 1-6
Author(s):  
Lisa Ragatz ◽  
Z.-Y. Jiang ◽  
C. E. Bauer ◽  
Howard Gest
Keyword(s):  
Photosynthetic Bacterium ◽  
Rhodospirillum Centenum ◽  
Phototactic Behavior ◽  
Purple Photosynthetic Bacterium

scholarly journals Isolation of Rhodospirillum centenumMutants Defective in Phototactic Colony Motility by Transposon Mutagenesis

1998 ◽  
Vol 180 (5) ◽  
pp. 1248-1255 ◽  
Author(s):  
Ze-Yu Jiang ◽  
Brenda G. Rushing ◽  
Yong Bai ◽  
Howard Gest ◽  
Carl E. Bauer
Keyword(s):  
Large Fraction ◽  
Photosynthetic Apparatus ◽  
Photosynthetic Bacterium ◽  
Continuous Illumination ◽  
Genetic Dissection ◽  
Rhodospirillum Centenum ◽  
Light Sensing ◽  
Purple Photosynthetic Bacterium ◽  
Agar Surface ◽  
Light Signals

ABSTRACT The purple photosynthetic bacterium Rhodospirillum centenum is capable of forming swarm colonies that rapidly migrate toward or away from light, depending on the wavelength of excitation. To identify components specific for photoperception, we conducted mini-Tn5-mediated mutagenesis and screened approximately 23,000 transposition events for mutants that failed to respond to either continuous illumination or to a step down in light intensity. A majority of the ca. 250 mutants identified lost the ability to form motile swarm cells on an agar surface. These cells appeared to contain defects in the synthesis or assembly of surface-induced lateral flagella. Another large fraction of mutants that were unresponsive to light were shown to be defective in the formation of a functional photosynthetic apparatus. Several photosensory mutants also were obtained with defects in the perception and transmission of light signals. Twelve mutants in this class were shown to contain disruptions in a chemotaxis operon, and five mutants contained disruptions of components unique to photoperception. It was shown that screening for photosensory defective R. centenumswarm colonies is an effective method for genetic dissection of the mechanism of light sensing in eubacteria.

The effect of respiration on the phototactic behavior of the purple nonsulfur bacterium Rhodospirillum centenum

1997 ◽  
Vol 167 (2-3) ◽  
pp. 99-105 ◽  
Author(s):  
Simona Romagnoli ◽  
Alejandro Hochkoeppler ◽  
Lars Damgaard ◽  
D. Zannoni
Keyword(s):  
Rhodospirillum Centenum ◽  
Phototactic Behavior ◽  
Purple Nonsulfur Bacterium

Reduction of the oxidized bacteriochlorophyll dimer in reaction centers by ferrocene is dependent upon the driving force

2007 ◽  
Vol 11 (03) ◽  
pp. 205-211 ◽  
Author(s):  
László Kálmán ◽  
Arlene L. M. Haffa ◽  
JoAnn C. Williams ◽  
Neal W. Woodbury ◽  
James P. Allen
Keyword(s):  
Electron Transfer ◽  
Rate Constants ◽  
Ph Dependence ◽  
Photosynthetic Bacterium ◽  
Energy Difference ◽  
Reaction Centers ◽  
Free Energy Difference ◽  
Midpoint Potential ◽  
Bacteriochlorophyll Dimer ◽  
Purple Photosynthetic Bacterium

The rates of electron transfer from ferrocene to the oxidized bacteriochlorophyll dimer, P , in reaction centers from the purple photosynthetic bacterium Rhodobacter sphaeroides, were measured for a series of mutants in which the P / P + midpoint potentials range from 410 to 765 mV (Lin et al. Proc. Natl. Acad. Sci. USA 1994; 91: 10265-10269). The observed rate constant for each mutant was found to be linearly dependent upon the ferrocene concentration up to 50 μM. The electron transfer is described as a second order reaction with rate constants increasing from 1.5 to 35 × 106 M -1. s -1 with increasing P / P + midpoint potential. This dependence was tested for three additional mutants, each of which exhibits a pH dependence of the P / P + midpoint potential due to an electrostatic interaction with an introduced carboxylic group (Williams et al. Biochemistry 2001; 40: 15403-15407). For these mutants, the pH dependence of the bimolecular rate constants followed a sigmoidal pattern that could be described with a Henderson-Hasselbalch equation, attributable to the change of the free energy difference for the reaction due to deprotonation of the introduced carboxylic side chains.

Sign in / Sign up

Export Citation Format

Share Document