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Journal of Bacteriology, March 2001, p. 1645-1654, Vol. 183, No. 5
Department of Microbiology and
Immunology3 and Program in Molecular
Biology,1 Loyola University Medical Center,
Maywood Illinois 60153, and Department of Biology, Virginia
Tech, Blacksburg, Virginia 240612
Received 28 June 2000/Accepted 4 December 2000
Bacterial spores are protected from the environment by a
proteinaceous coat and a layer of specialized peptidoglycan called the
cortex. In Bacillus subtilis, the attachment of the coat to the spore surface and the synthesis of the cortex both depend on
the spore protein SpoIVA. To identify functionally important amino acids of SpoIVA, we generated and characterized strains bearing random point mutations of spoIVA that result in
defects in coat and cortex formation. One mutant resembles the null
mutant, as sporulating cells of this strain lack the cortex and the
coat forms a swirl in the surrounding cytoplasm instead of a shell around the spore. We identified a second class of six mutants with
a partial defect in spore assembly. In sporulating cells of these
strains, we frequently observed swirls of mislocalized coat in addition
to a coat surrounding the spore, in the same cell. Using
immunofluorescence microscopy, we found that in two of these mutants,
SpoIVA fails to localize to the spore, whereas in the remaining
strains, localization is largely normal. These mutations identify amino
acids involved in targeting of SpoIVA to the spore and in
attachment of the coat. We also isolated a large set of mutants
producing spores that are unable to maintain the dehydrated state.
Analysis of one mutant in this class suggests that spores of this
strain accumulate reduced levels of peptidoglycan with an altered structure.
0021-9193/01/$04.00+0 DOI: 10.1128/JB.183.5.1645-1654.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Amino Acids in the Bacillus subtilis Morphogenetic
Protein SpoIVA with Roles in Spore Coat and Cortex
Formation
*
Corresponding author. Mailing address: Department of
Microbiology and Immunology, Loyola University Medical Center, 2160 South First Ave., Maywood IL 60153. Phone: (708) 216-3706. Fax: (708) 216-9574. E-mail: adriks{at}luc.edu.
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