Size of bacterial ice-nucleation sites measured in situ by radiation inactivation analysis

Journal Article · Tue Mar 01 00:00:00 EST 1988 · Proc. Natl. Acad. Sci. U.S.A.; (United States)

DOI:https://doi.org/10.1073/pnas.85.5.1334· OSTI ID:6656640

Govindarajan, A G; Lindow, S E

Four bacterial species are known to catalyze ice formation at temperatures just below 0/sup 0/C. To better understand the relationship between the molecular structure of bacterial ice-nucleation site(s) and the quantitative and qualitative features of the ice-nucleation-active phenotype, the authors determined by ..gamma..-radiation analysis the in situ size of ice-nucleation sites in strains of Pseudomonas syringae and Erwinia herbicola and in Escherichia coli HB101 carrying the plasmid pICE1.1. Lyophilized cells of each bacterial strain were irradiated with a flux of ..gamma.. radiation from 0 to 10.2 Mrad. Differential concentrations of active ice nuclei decreased as a first-order function of radiation dose in all strains as temperature was decreased from -2/sup 0/C to -14/sup 0/C in 1/sup 0/C intervals. Sizes of ice nuclei were calculated from the /sup +/-radiation flux at which 37% of initial ice nuclei active within each 1/sup 0/C temperature interval remained. The minimum mass of a functional ice nucleus was about 150 kDa for all strains. The size of ice nuclei increased logarithmically with increasing temperature from -12/sup 0/CC to -2/sup 0/C, where the estimated nucleant mass was 19,000 kDa. The ice nucleant in these three bacterial species may represent an oligomeric structure, composed at least in part of an ice gene product that can self-associate to assume many possible sizes.

• Research Organization: Univ. of California, Berkeley (USA)
• OSTI ID: 6656640
• Journal Information: Proc. Natl. Acad. Sci. U.S.A.; (United States), Vol. 85:5
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BACTERIA
BIOLOGICAL RADIATION EFFECTS
ICE
NUCLEATION
PROTEINS
MOLECULAR STRUCTURE
CELL MEMBRANES
CLIMATES
COBALT 60
ESCHERICHIA COLI
GAMMA RADIATION
GENES
INACTIVATION
LYOPHILIZATION
PSEUDOMONAS
TEMPERATURE DEPENDENCE
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL EFFECTS
CELL CONSTITUENTS
COBALT ISOTOPES
ELECTROMAGNETIC RADIATION
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
IONIZING RADIATIONS
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MEMBRANES
MICROORGANISMS
MINUTES LIVING RADIOISOTOPES
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
RADIATION EFFECTS
RADIATIONS
RADIOISOTOPES
YEARS LIVING RADIOISOTOPES
560130* - Radiation Effects on Microorganisms