Crystal Structures of Two Archaeal 8-Oxoguanine DNA Glycosylases Provide Structural Insight into Guanine/8-Oxoguanine Distinction

Abstract

Summary Among the four DNA bases, guanine is particularly vulnerable to oxidative damage and the most common oxidative product, 7,8 dihydro-8-oxoguanine (8-oxoG), is the most prevalent lesion observed in DNA molecules. Fortunately, 8-oxoG is recognized and excised by the 8-oxoguanine DNA glycosylase (Ogg) of the base excision repair pathway. Ogg enzymes are divided into three separate families, namely Ogg1, Ogg2, and AGOG. To date, structures of members of both Ogg1 and AGOG families are known but no structural information is available for members of Ogg2. Here we describe the first crystal structures of two archaeal Ogg2: Methanocaldococcus janischii Ogg (MjaOgg) and Sulfolobus solfataricus Ogg (SsoOgg). A structural comparison with OGG1 and AGOG suggested that the C-terminal lysine of Ogg2 may play a key role in discriminating between guanine and 8-oxoG. This prediction was substantiated by measuring the glycosylase/lyase activity of a C-terminal deletion mutant of MjaOgg.

The C-terminal Lysine of Ogg2 DNA Glycosylases is a Major Molecular Determinant for Guanine/8-Oxoguanine Distinction

“…Phenix.automr 28 found the correct solution for the four molecules with LLG=1294 and R=0.354 using the apo-MjaOgg structure 17 as search model. The resulting electron density map was well defined and density was observed for the four protein/DNA complexes (see figure 1).…”

“…14 Ogg2 was the last Ogg family to be structurally characterized and comprises primarily archaeal enzymes, such as Methanocaldococcus janischii Ogg (MjaOgg) and Sulfolobulus solfataricus Ogg (SsoOgg). 17 Ogg2 glycosylases comprise two domains separated by the HhH motif and, in contrast to Ogg1, are less variable in size (± 207 amino acids). 18; 19; 20; 21 Ogg2 enzymes also display a less stringent opposite base specificity than Ogg1.…”

“…17 Ogg2 glycosylases comprise two domains separated by the HhH motif and, in contrast to Ogg1, are less variable in size (± 207 amino acids). 18; 19; 20; 21 Ogg2 enzymes also display a less stringent opposite base specificity than Ogg1. 19; 21 Finally, members of the third family, AGOG, share a similar two-domain architecture with Ogg2.…”

“…Ogg2 members lack the αA-βB loop used by Ogg1 to specifically interact with 8-oxoG and until recently, it was unclear how Ogg2 would select for 8-oxoG. We previously reported the unliganded crystal structures of two members of the Ogg2 family, MjaOgg and SsoOgg, 17 and predicted that the conserved C-terminal lysine would play a crucial role in the distinction between 8-oxoG and G in this family of enzymes.…”

Structural basis for the lack of opposite base specificity of Clostridium acetobutylicum 8-oxoguanine DNA glycosylase

“…The Ogg DNA glycosylases belong to three different families: Ogg1, which includes the well characterized human OGG1 (hOGG1) and the bacterial Clostridium acetobutylicum Ogg (CacOgg) [11–19], Ogg2 which was the last Ogg family to be structurally characterized and comprises mostly archaeal enzymes [20, 21] and finally, AGOG (Archaeal GO Glycosylase) [22] represented by Pyrobaculum aerophilum AGOG (Pa-AGOG). [23, 24] Overall CacOgg shares a similar tertiary fold with hOGG1.…”