Regulation of high-affinity leucine transport in escherichia coli

Leucine is transported into E coli by two osmotic shock-sensitive, high-affinity systems (LIV-I and leucine-specific systems) and one membrane bound, low-affinity system (LIV-II). Expression of the high-affinity transport systems is altered by mutations in liv R and 1st R , genes for negatively acting regulatory elements, and by mutations in rho , the gene for transcription termination. All four genes for high-affinity leucine transport ( livJ, livK, livH , and livG ) are closely linked and have been cloned on a plasmid vector, pOX1. Several subcloned fragments of this plasmid have been prepared and used in complementation and regulation studies. The results of these studies suggest that livJ and livK are separated by approximately one kilobase and give a gene order of livJ–livK–livH. livJ and livK appear to be regulated in an interdependent fashion; livK is expressed maximally when the livJ gene is inactivated by mutation or deletion. The results support the existence of separate promoters for the livJ and livK genes. The effects of mutations in the rho and livR genes are additive on one another and therefore appear to be involved in independent regulatory mechanisms. Mutations in the rho gene affect both the LIV-I and leucinespecific transport systems by increasing the expression of livJ and livK , genes for the LIV-specific and leucine-specific binding proteins, respectively.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/38209/1/400140410_ftp.pd

The C-terminal cytoplasmic tail of herpes simplex virus type 1 gE protein is phosphorylated in vivo and in vitro by cellular enzymes in the absence of other viral proteins

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Mutational analysis of the ICP4 binding sites in the 5' transcribed noncoding domains of the herpes simplex virus 1 UL 49.5 gamma 2 gene.

A previous report (P. Mavromara-Nazos and B. Roizman, Proc. Natl. Acad. Sci. USA 86:4071-4075, 1989) demonstrated that substitution of sequences of the thymidine kinase (tk) gene, a beta gene, extending from -16 to +51 with sequences extending from -12 to +104 of the gamma 2 UL 49.5 gene in viral recombinant R3820 conferred upon the chimeric gene gamma 2 attributes in the context of the viral genome in a productive infection. The UL49.5 gene sequences extending from -179 to +104 contain four DNA binding sites for the major regulatory protein ICP4. Of these sites, two map between nucleotides +20 and +80 within the sequence which confers gamma 2 regulation upon the chimeric gene. To determine the role of these ICP4 binding sites in conferring the gamma 2 gene attributes, sequences comprising the two ICP4 binding sites were mutagenized and used to reconstruct the R3820 recombinant virus. In addition, a new recombinant virus (R8023) was constructed in which tk sequences extending from -240 to +51 were replaced with wild-type or mutated sequences contained between nucleotides -179 to +104 of the UL 49.5 gene. Vero cells infected with the recombinant viruses in the presence or absence of phosphonoacetate, a specific inhibitor of viral DNA synthesis, were then tested for accumulation of tk RNA by using an RNase protection assay. The results indicate that in the recombinant R3820, a mutation which destroyed one of the two UL49.5 ICP4 DNA binding sites significantly reduced the accumulation of tk RNA at both early and late times after infection. The effect of this mutation was less pronounced in cells infected with the R8023 virus, whose chimeric tk gene contains the two upstream UL49.5 ICP4 binding sites. None of the mutations affected the sensitivity of the chimeric genes to phosphonoacetate. The mutated site appears to be involved in the accumulation of RNA

Detection of human papillomaviruses in squamous cell carcinomas of the lung

The aim of this study was to evaluate the possible association of human papillomaviruses (HPV) with the development of squamous cell lung carcinomas (SqCLCs). Tissue material from 52 cases of SqCLCs were studied, and the data were evaluated according to the degree of differentiation, HPV presence and type. Analysis was performed by polymerase chain reaction (PCR) method using consensus primers, and the results were confirmed by subsequent Southern blot hybridization. Overall, the results showed 69% positivity (n=32). Forty-one cases were examined for the presence of specific HPV types (6/11 and 16/18) by hybridization of the PCR products with P-32-labelled probes. HPV 6/11 types were detected in 6 of the 29 positive cases (20.6%). HPV 16/18 types were the most prevalent types, and were detected in 11/29 cases (37.9%: 4/10 of well-differentiated cases, 6/25 of moderately and 1/6 of poorly differentiated carcinomas). Our results confirm the possibility that HPV might play a role in the development of SqCLCs and suggest a possible relation of high-risk HPV16/18 types to tumour differentiation