A deoxycytidine kinase-deficient variant of a human promyelocytic leukemic Å“il line (HL-60/ara-C) has been isolated and characterized. These cells are capable of proliferating in the presence of 10~6 M 1-/3-o-arabinofuranosylcytosine (ara-C), a level achieved in the plasma of leukemic patients undergoing conventional-dose ara-C therapy. The cells share numerous biological and biochemical featu...

Two mutant strains of Yersinia pestis KIM5+, a Deltacrp mutant and a mutant with arabinose-dependent regulated delayed-shutoff crp expression (araC P(BAD) crp), were constructed, characterized in vitro, and evaluated for virulence, immunogenicity, and protective efficacy in mice. Both strains were highly attenuated by the subcutaneous (s.c.) route. The 50% lethal doses (LD(50)s) of the Deltacrp...

In the bacterium Escherichia coli, the AraC protein positively and negatively regulates expression of the proteins required for the uptake and catabolism of the sugar L-arabinose. This essay describes how work from my laboratory on this system spanning more than thirty years has aided our understanding of positive regulation, revealed DNA looping (a mechanism that explains many action-at-a-dist...

A f&-structure physical and genetic m&p wt~s constructed of a 1000 base-pair region of t,he L-arabinose operon of Escherichia coEi. This region consists of the ara regulatory sequences contained between the araC and araB genes and portions of these flanking genes. Point mutations, Mu phage insertions, and bacterial deletions 8s well as arabinose-induced and basal enzyme levels in the strains we...

HE L-arabinose-gene complex in Escherichia coli B/r is a regulon (MAAS and CLARK 1964) corisisting of at least two operons controlled by regulator gene araC. One operon consists of structural genes, araD (L-ribulose 5-phosphate 4-epimerase), araA (L-arabinose isomerase), and araB (L-ribulokinase) , and controlling sites, araZ (initiator) and araO (operator). These genetic units are linked in th...