19F NMR reveals dynamics not evident in crystal structure of long-chain flavodoxin

Flavodoxin (Fld) is a small FMN containing protein that is involved in single electron transfer. The Long-chain flavodoxin in Rhodopseudomonas palustris bacteria replaces ferredoxin as a low-potential electron carrier when iron is scarce. Thus, it is proposed to interact with the bifurcating electron transfer flavoprotein (ETF) that yields low-potential electrons. A surface loop on Fld interacts with another of Fld's partner proteins, so we hypothesize that it also mediates Fld's interaction with ETF. To monitor interactions with ETF directly and investigate dynamics in this loop, we are using 19F NMR in solution. 19F is hyperresponsive to changes in its chemical environment with a chemical shift range of >300 ppm. To provide a static reference point and assess structural heterogeneity, we are also exploiting X-ray crystallography.