Structural role of conserved Asn179 in the short-chain dehydrogenase/reductase scaffold

Short-chain dehydrogenases/reductases (SDR) constitute a large family of enzymes found in all forms of life. Despite a low level of sequence identity, the three-dimensional structures determined display a nearly superimposable alpha/beta folding pattern. We identified a conserved asparagine residue located within strand betaF and analyzed its role in the short-chain dehydrogenase/reductase architecture. Mutagenetic replacement of Asn179 by Ala in bacterial 3 beta /17 beta -hydroxysteroid dehydrogenase yields a folded, but enzymatically inactive enzyme, which is significantly more resistant to denaturation by guanidinium hydrochloride. Crystallographic analysis of the wild-type enzyme at 1.2-Angstrom resolution reveals a hydrogen bonding network, including a buried and well-ordered water molecule connecting strands betaE to betaF, a common feature found in 16 of 21 known three-dimensional structures of the family. Based on these results, we hypothesize that in mammalian 11 beta -hydroxysteroid dehydrogenase the essential Asn-linked glycosylation site, which corresponds to the conserved segment, displays similar structural features and has a central role to maintain the SDR scaffold.

Nordling, E (författare)
Benach, J (författare)
Berndt, Kurt DKarolinska Institutet,Södertörns högskola,Avdelning Naturvetenskap,Karolinska Institute(Swepub:sh)SHKTBT (författare)
Ladenstein, RKarolinska Institutet (författare)
Jörnvall, HKarolinska Institutet (författare)
Oppermann, U (författare)
Södertörns högskolaAvdelning Naturvetenskap (creator_code:org_t)

Ingår i:Biochemical and Biophysical Research Communications - BBRC: Elsevier BV289:3, s. 712-7170006-291X1090-2104

Av författaren/redakt...: Filling, C; Nordling, E; Benach, J; Berndt, Kurt D; Ladenstein, R; Jörnvall, H; visa fler...; Oppermann, U; visa färre...

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