Type II Kinase Inhibitors Targeting Cys-Gatekeeper Kinases Display Orthogonality with Wild Type and Ala/Gly-Gatekeeper Kinases

Analogue-sensitive (AS) kinases contain large to small mutations in the gatekeeper position rendering them susceptible to inhibition with bulky analogues of pyrazolopyrimidine-based Src kinase inhibitors (e.g., PP1). This “bump-hole” method has been utilized for at least 85 of ∼520 kinases, but many kinases are intolerant to this approach. To expand the scope of AS kinase technology, we designed type II kinase inhibitors, ASDO2/6 (analogue-sensitive “DFG-out” kinase inhibitors 2 and 6), that target the “DFG-out” conformation of Cys-gatekeeper kinases with submicromolar potency. We validated this system in vitro against Greatwall kinase (GWL), Aurora-A kinase, and cyclin-dependent kinase-1 and in cells using M110C-GWL-expressing mouse embryonic fibroblasts. These Cys-gatekeeper kinases were sensitive to ASDO2/6 inhibition but not AS kinase inhibitor 3MB-PP1 and vice versa. These compounds, with AS kinase inhibitors, have the potential to inhibit multiple AS kinases independently with applications in systems level and translational kinase research as well as the rational design of type II kinase inhibitors targeting endogenous kinases

Metabolic Engineering of Cofactor F420 Production in Mycobacterium smegmatis

Cofactor F420 is a unique electron carrier in a number of microorganisms including Archaea and Mycobacteria. It has been shown that F420 has a direct and important role in archaeal energy metabolism whereas the role of F420 in mycobacterial metabolism has only begun to be uncovered in the last few years. It has been suggested that cofactor F420 has a role in the pathogenesis of M. tuberculosis, the causative agent of tuberculosis. In the absence of a commercial source for F420, M. smegmatis has previously been used to provide this cofactor for studies of the F420-dependent proteins from mycobacterial species. Three proteins have been shown to be involved in the F420 biosynthesis in Mycobacteria and three other proteins have been demonstrated to be involved in F420 metabolism. Here we report the over-expression of all of these proteins in M. smegmatis and testing of their importance for F420 production. The results indicate that co–expression of the F420 biosynthetic proteins can give rise to a much higher F420 production level. This was achieved by designing and preparing a new T7 promoter–based co-expression shuttle vector. A combination of co–expression of the F420 biosynthetic proteins and fine-tuning of the culture media has enabled us to achieve F420 production levels of up to 10 times higher compared with the wild type M. smegmatis strain. The high levels of the F420 produced in this study provide a suitable source of this cofactor for studies of F420-dependent proteins from other microorganisms and for possible biotechnological applications