Bifunctional Gene ClusterlnqBCDEFMediates Bacteriocin Production and Immunity with Differential Genetic Requirements

ABSTRACTA comprehensive gene disruption of lacticin Q biosynthetic clusterlnqQBCDEFwas carried out. The results demonstrated the necessity of the complete set oflnqQBCDEFfor lacticin Q production, whereas immunity was flexible, with LnqEF (ABC transporter) being essential for and LnqBCD partially contributing to immunity.

Prothrombin G20210A is a Bifunctional Gene Polymorphism

SummaryThe G20210A polymorphism has been shown to alter the efficiency of prothrombin mRNA processing. Here we show that the G20210A mutation also alters prothrombin mRNA stability. Three-fold more prothrombin protein and mRNA were produced in NIH-3T3 cells transfected with the prothrombin cDNAs containing the 20210A variant compared to cells expressing the 20210G variant. mRNA stability assays using chimeric globin transcripts harboring the G or A variant of the 97 nt prothrombin 3’-UTR indicated that the 20210G variant conferred greater instability to the globin reporter transcript than the A variant in transfected HepG2 cells. Both variants of the prothrombin 3’-UTR were shown to provide binding sites for a number of cellular proteins including HuR, an RNA binding protein associated with mRNA stability. Our results indicate that the G20210A is a bifunctional polymorphism, as it not only alters the efficiency of mRNA processing, but also the decay rate of prothrombin mRNA.

Genetics of lycopene cyclization and substrate transfer in β-carotene biosynthesis inPhycomyces

SUMMARYThe mutations which block lycopene cyclization and those which stop substrate transfer along the carotene pathway are very closely linked inPhycomyces. Simultaneous blocking of both processes commonly results from single exposures to mutagens; and both blockings may be simultaneously removed after a second exposure. The frequencies of different kinds of mutants after treatments with the mutagensN-methyl-N′-nitro-N-nitrosoguanidine and ICR-170, their reversion patterns, and recombination analyses indicate that lycopene cyclization and substrate transfer are governed by separate segments of a single bifunctional gene.

GENETICS OF ARGININE BIOSYNTHESIS IN NEUROSPORA CRASSA

ABSTRACT A large number of arginine-requiring mutants of Neurospora was isolated, using a strain already partially impaired in an enzyme of the pathway. Among the mutants, all previously described loci, except one, were represented, and several new loci were defined and mapped. Four groups of mutants were of particular interest. First, thc large group of arg-6 mutants, when tested for intragenic complementation, suggested a bifunctional gene, possibly controlling two steps in ornithine synthesis. This is consistent with the limited enzymic information about this locus. Second, the arg-13 locus was represented by 14 new mutants. All five tested were quite leaky. suggesting that the function controlled by this gene can be rarried out to a limited extent spontaneously or by another gene product. Third, a new locus, arg-14, was defined. It controls a step in ornithine synthesis. It lies in a 1 to 2 map-unit interval between arg-2 and pyr-3 on LG IVR, as shown by mapping in relation tG translocation breakpoints. Fourth, a second new locus whose mutants render the partial mutation in starting material auxotrophic was defined and mapped near the centromere of LG VIL. These new mutants are unable to derepress enzymes of the pathway and may qualify as regulatory mutants.