We isolated nonsense mutants of bacteriophage PRD1, a lipid-containing polyhedral virus capable of infecting many genera of gram-negative bacteria. These mutants were grouped into 19 classes on the basis of genetic complementation and sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis. PRD1 infection led to the synthesis of at least 25 viral proteins, 17 of which were components of mature virions. The synthesis of proteins fell into the following three classes: very early, middle early, and late. Two of the very early proteins, P1 and P8, had an effect on DNA synthesis, host protein synthesis shutoff, and the turning on of middle and late protein synthesis. Another very early protein, P12, was involved in the shutoff of early protein synthesis. Two genes were identified as affecting lysis of the host. One appeared to be a lysin, whereas the other was an accessory lytic factor.
Several antibiotic resistance markers in
Bacillus subtilis
have been mapped by three-factor transduction crosses using bacteriophage PBS1. These markers, which are thought to be located in genes coding for ribosomal proteins, are within a segment comprising about 5 per cent of the
B. subtilis
genetic map, close to the major group of rRNA cistrons. The order of genetic makers in this region was found to be
cysA14 mic-1
†
str-1
(
ery-1, ole-2
)
spc-2 bry-2 lin-2
. The positions of
neo-2, nea-1
, and
kan-2
are uncertain, although they are located in this region to the right of
cysA14
.
Mutations governing resistance to neamine, neomycin, kanamycin and fusidic acid have been mapped within the ribosomal region of the Bacillus subtilis genome using PBSl-mediated transduction. The probable order of these closely linked markers is:neo-2
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