Catalyzes the coenzyme F420-dependent oxidation of glucose 6-phosphate (G6P) to 6-phosphogluconolactone. Appears to have a role in resistance to oxidative stress, via its consumption of G6P that serves as a source of reducing power to combat oxidative stress in mycobacteria. Cannot use NAD, NADP, FAD or FMN instead of coenzyme F420 as an electron acceptor. Exhibits nearly no activity with D-mannose-6-phosphate or D-fructose-6-phosphate as substrate. D-glucose 6-phosphate + H(+) + oxidized coenzyme F420-(gamma-L-Glu)(n) = 6-phospho-D-glucono-1,5-lactone + reduced coenzyme F420-(gamma-L-Glu)(n) Optimum pHs are 5.5 and 8.0. Optimum temperature is 60 degrees Celsius. Homodimer. Cells lacking this gene are more sensitive than the wild-type to oxidative stress induced by plumbagin and menadione. They display decreased ability to consume G6P and reduce plumbagin and menadione when exposed to these agents. Exhibits Si-face stereospecificity with respect to C5 of coenzyme F420. Belongs to the F420-dependent glucose-6-phosphate dehydrogenase family. Extended N-terminus.