Bulletin Number Four 1985

how it works. From the industrial point o f view, aerobic fermentation turns nutrients into useless carbondioxide and water, but anaerobic fermentation converts nutrients into products o f value. Thus, studying the mechanism o f switch between aerobic and anaerobic metabolism is a crucial step in ex ploiting the use o f microorganisms for industrial applications. In this respect, the Pasteur control protein appears to be one o f the key factors. A t Imperial College ， London, I succeeded in cloning the Pasteur control protein mutant gene adhC while I was on leave from the University. Since my return I have repeated this cloning operation partly to gear up our laboratory in cloning experi ments and partly to get a clone w ith short insert for easy nucleotide sequencing. With this clone, we can modify the aerobic and anaerobic switch system to suit various industrial processes, or use it as a probe to clone similar control gene in yeast or other organ isms. We can also put this Pasteur control protein gene into an expression vector to over produce this protein and use this protein to identify the aerobic- anaerobic switch effector. The Pasteur control protein mutant gene cloned in plasmid Vector pUC18 showed many unusual physiological properties. By studying the property o f this clone, one can understand the function o f this Pasteur control protein. Since the aerobic and anaerobic metabolic switch is so important in industry, any understanding along this line may be useful. For genetic manipulations, the extent o f ex pression by the cloned gene is obviously o f importance. T4 early and late genes cloned into Lambda vector were used as a model system. The expression o f different T4 early genes and late genes was measured. It was surprising that some T4 early genes have a high rate o f expression while others have hardly any expression at all. The expression o f bacteriophage T4 late genes was also not expected. Subcloning and nucleotide sequencing o f the Pasteur control protein mutant gene adhC *Drs. K.K. Mark & H.S. Kwan, Department o f Bio logy, Dr. W.K.K. Ho ， Department o f Biochemistry The Pasteur control protein gene w ith mutation that over produces alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (AcDH) has been cloned by Dr. K.K. Mark during his sabbatical leave in Professor B.S. Hartley's laboratory. An obvious extension o f this work is to subclone this mutant gene into small DNA fragments and determine their nucleotide sequences. As a similar Pasteur control protein gene,fn r was cloned and sequenced, and acom parison between the two clonings could yield signifi cant information. We w ill make attempts to clone and sequence the alcohol dehydrogenase (ADH) structural gene. This structural gene should have a nucleotide sequence in its promoter which is recog nized by the Pasteur control protein adhC. Screening o f C-DNA Libraries for Useful Proteins *Drs. W.K.K. Ho & W. M. Keung ， Department o f Biochemistry Developments in recombinant DNA technology have enabled scientists to construct C-DNA libraries from messenger RNA extracted from different tissues. These C-DNA's can be cloned and isolated. After proper packaging o f them into a host/vector system, the information residing in them can be transcribed and made to synthesize different proteins and en zymes. Using this approach, a number o f useful proteins have been made. The most noteworthy o f them perhaps are insulin and interferon. Our research project in this direction en compasses the screening o f a liver C-DNA library for the enzyme alcohol dehydrogenase. We hope to isolate the segment o f DNA coding for this enzyme. Once this is done ， we can proceed to prepare a DNA probe to examine the genetics o f metabolism relating to this enzyme. In addition to the liver, we are also interested in the C-DNA library o f the brain. A variety o f neuropeptides exists in this organ and some o f them may have high pharmacological values. Our aim is to make use o f the C-DNA technique to efficiently synthesize these peptides in the bacteria. In the long run, we hope to master this technology and to expand our work to synthesize proteins and enzymes o f industrial interest. This project is carried out in collaboration w ith Dr. W.Y. Chan, Department o f Biochemistry and Pediatrics, Oklahoma University. Protein Engineering o f Trichosanthin, α - and β - Momorcharin *Dr. H. W. Yeung, Department o f Biochemistry We have been studying the biochemistry and pharmacology o f abortifacient proteins from the Cucurbitaceae family since 1978, particularly on Trichosanthin (first discovered in China) and α - and β -momorcharin (first discovered in this Univer sity). From the studies carried out at this University and those in China, these proteins were found to be very effective in inducing mid-term abortion and the termination o f early pregnancy in laboratory animals and humans. Clinical studies in China have shown that trichosanthin is more effective than the well-known abortifacient, prostaglandin F2 α . We have also demonstrated the anti-cancer effect o f these proteins. 22 RECENT DEVELOPMENTS