DETERMINANTS FOR OVERPRODUCTION OF THE PSEUDOMONAS-OLEOVORANS CYTOPLASMIC MEMBRANE-PROTEIN ALKANE HYDROXYLASE IN ALK(-COLI W3110() ESCHERICHIA)

The Pseudomonas oleovorans alkB gene is expressed in alk(+) Escherichi a coli W3110 to 10 to 15% of the total cell protein, which is exceptio nal for a (foreign) cytoplasmic membrane protein, In other E. coli rec ombinants such as alk(+) HB101, AlkB constitutes 2 to 3% of the total protein. In this study, we have investigated which factors determine t he expression level of alkB in alk(+) W3110. In particular, we have in vestigated the role of AlkB induced stimulation of phospholipid synthe sis, Blocking phospholipid synthesis in alk(+) W3110 did not specifica lly alter the expression of alkB, and we conclude that stimulation of phospholipid synthesis is not a prerequisite for high-level expression of the membrane protein, W3110 is able to produce exceptionally high levels of alkane monooxygenase, because the rate of alkB mRNA synthesi s in W3110 is an order of magnitude higher than that in HB101. This ma y be due in part to the higher copy number of pGEc47 in W3110 in compa rison with HB101.