Alterations of the portal protein, gpB, of bacteriophage lambda suppress mutations in cosQ, the site required for termination of DNA packaging.
The cosQ site of bacteriophage lambda is required for DNA packaging termination. Previous studies have shown that cosQ mutations can be suppressed in three ways: by a local suppressor within cosQ, an increase in the length of the lambda chromosome, and missense mutations affecting the prohead's portal protein, gpB. In the present work, revertants of a set of lethal cosQ mutants were screened for suppressors. Seven new cosQ suppressors affected gene B, which encodes the portal protein of the prohead. All seven were allele-nonspecific suppressors of cosQ mutations. Experiments with several phages having two cosQ suppressors showed that the suppression effects were additive. Furthermore, these double suppressors had minimal effects on the growth of cosQ(+) phages. These trans-acting suppressors affecting the portal protein are proposed to allow the mutant cosQ site to be more efficiently recognized, due to the slowing of the rate of translocation.
Wieczorek
Douglas J
DJ
Genetics Ph.D. Program and Department of Microbiology, University of Iowa, Iowa City, Iowa 52242, USA. wieczorekd@mail.medicine.uiowa.edu
Didion
Lisa
L
Feiss
Michael
M
D000483:Alleles; D000595:Amino Acid Sequence; D010582:Bacteriophage lambda / Q000235:genetics*; D001483:Base Sequence; D004261:DNA Replication; D004279:DNA, Viral / Q000378:metabolism*; D004706:Endodeoxyribonucleases; D004926:Escherichia coli / Q000235:genetics; D015967:Gene Expression Regulation, Viral; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013489:Suppression, Genetic; D014764:Viral Proteins / Q000235:genetics*; D014779:Virus Replication / Q000235:genetics / Q000502:physiology
D004279:DNA, Viral; D014764:Viral Proteins; D004706:Endodeoxyribonucleases; C030894:terminase