Catalyzes the NADPH-dependent reduction of [LysW]-aminoadipate 6-phosphate to yield [LysW]-aminoadipate 6-semialdehyde. [amino-group carrier protein]-C-terminal-N-(1-carboxy-5-oxopentan-1-yl)-L-glutamine + NADP(+) + phosphate = [amino-group carrier protein]-C-terminal-N-(1-carboxy-5-phosphooxy-5-oxopentan-1-yl)-L-glutamine + H(+) + NADPH Amino-acid biosynthesis; L-lysine biosynthesis via AAA pathway; L-lysine from L-alpha-aminoadipate (Thermus route): step 3/5. Belongs to the NAGSA dehydrogenase family. Type 1 subfamily. LysY sub-subfamily.