Factors influencing germination of Bacillus subtilis spores via activation of nutrient receptors by high pressure.
Different nutrient receptors varied in triggering germination of Bacillus subtilis spores with a pressure of 150 MPa, the GerA receptor being more responsive than the GerB receptor and even more responsive than the GerK receptor. This hierarchy in receptor responsiveness to pressure was the same as receptor responsiveness to a mixture of nutrients. The levels of nutrient receptors influenced rates of pressure germination, since the GerA receptor is more abundant than the GerB receptor and elevated levels of individual receptors increased spore germination by 150 MPa of pressure. However, GerB receptor variants with relaxed specificity for nutrient germinants responded as well as the GerA receptor to this pressure. Spores lacking dipicolinic acid did not germinate with this pressure, and pressure activation of the GerA receptor required covalent addition of diacylglycerol. However, pressure activation of the GerB and GerK receptors displayed only a partial (GerB) or no (GerK) diacylglycerylation requirement. These effects of receptor diacylglycerylation on pressure germination are similar to those on nutrient germination. Wild-type spores prepared at higher temperatures germinated more rapidly with a pressure of 150 MPa than spores prepared at lower temperatures; this was also true for spores with only one receptor, but receptor levels did not increase in spores made at higher temperatures. Changes in inner membrane unsaturated fatty acid levels, lethal treatment with oxidizing agents, or exposure to chemicals that inhibit nutrient germination had no major effect on spore germination by 150 MPa of pressure, except for strong inhibition by HgCl2.
Black
Elaine P
EP
Department of Molecular, Microbial, and Structural Biology, University of Connecticut Health Center, Farmington, CT 06032, USA.
Koziol-Dube
Kasia
K
Guan
Dongsheng
D
Wei
Jie
J
Setlow
Barbara
B
Cortezzo
Donnamaria E
DE
Hoover
Dallas G
DG
Setlow
Peter
P
D001412:Bacillus subtilis / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D001426:Bacterial Proteins; D003470:Culture Media; D015964:Gene Expression Regulation, Bacterial; D006874:Hydrostatic Pressure; D008565:Membrane Proteins; D008627:Mercuric Chloride / Q000494:pharmacology; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D013171:Spores, Bacterial / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism
D001426:Bacterial Proteins; D003470:Culture Media; C096462:GerAB protein, Bacillus subtilis; D008565:Membrane Proteins; D011956:Receptors, Cell Surface; D008627:Mercuric Chloride