Expression of double vitrescilla hemoglobin enhances growth and alters ribosome and tRNA levels in escherichia coli

摘要

In several organisms,expression of a gene encoding dimeric hemoglobin(VHb) from the obligate aerobic bacterium Vitreoscilla stercoraria has been shown to increase microaerobic cell growth and enhance oxygen-dependent cell metabolism.In an attempt to further improve these effects of VHb,a gene encoding two vhb genes connected by a short linker of six base paris was constructed and expressed in Escherichia coli (double VHb).Escherichia coli cells expressing doulbe VHbreached a cell density 19% higher than that of cells expressing native VHb.The protein production per cell remained constant since the increasein cell growth was accompained by an increase inprote incontent by 16%.Investigation of ribosome and tRNA content revealed that cells expressing double VHb reached their maximalcapacity of proteinsynthesis later during cultivation than cells expressing native VHb,and further more they reached considerably higher levels of ribosome and tRNA compared tothat of the VHb-expressing cells.