Abstract
The products of genes 40 and 20 act early in the T4 head assembly pathway. A lesion inactivating either p40 or p20 results in the same phenotype: the production of aberrant tubular heads. The gene 20 product is required in stoichiometric amounts during head assembly and is a minor protein component of the capsid. However, the function of p40 in head assembly is probably catalytic. It is not found in phage capsids. Two new amber mutants in gene 40 were isolated using a new (for T4) selection method. The map positions of the mutants were established by two- and three-factor crosses. Two “hot spots” of mutational repeats exist. In addition, gene 40 was found to map between genes 41 and 42, not between genes 58–61 and 41 as previously published. The new mutants have a peculiar temperature-sensitive phenotype. They can grow on am restrictive hosts at 30° but cannot grow at 40.5°; however, they grow on am permissive hosts as well as wild-type phage does at both temperatures.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
