NdbA, one of the three type 2 NAD(P)H dehydrogenases (NDH-2) in Synechocystis sp. PCC 6803 (hereafter Synechocystis)
was here localized to the thylakoid membrane (TM), unique for the three
NDH-2s, and investigated with respect to photosynthetic and cellular
redox metabolism. For this purpose, a deletion mutant (ΔndbA) and a complementation strain overexpressing NdbA (ΔndbA::ndbA) were constructed. It is demonstrated that NdbA is expressed at very low level in the wild-type (WT) Synechocystis
under photoautotrophic (PA) growth whilst substantially higher
expression occurs under light-activated heterotrophic growth (LAHG). The
absence of NdbA resulted in non-optimal growth of Synechocystis
under LAHG and concomitantly enhanced the expression of
photoprotection-related flavodiiron proteins and carbon
acquisition-related proteins as well as various transporters, but
downregulated a few iron homeostasis-related proteins. NdbA
overexpression, on the other hand, promoted photosynthetic pigmentation
and functionality of photosystem I under LAHG conditions while distinct
photoprotective and carbon concentrating proteins were downregulated.
NdbA overexpression also exerted an effect on the expression of many
signaling and gene regulation proteins. It is concluded that the amount
and function of NdbA in the TM has a capacity to modulate the redox
signaling of gene expression, but apparently has a major physiological
role in maintaining iron homeostasis under LAHG conditions. LC-MS/MS
data are available via ProteomeXchange with identifier PXD011671.