The Sac10b family proteins, also named as Alba, are small, basic, nucleic acid-binding proteins widely distributed in archaea. They possess divergent physiological functions such as binding to both DNA and RNA with a high affinity and involving in genomic DNA compaction, RNA transactions and transcriptional regulations. The structures of many Sac10b family proteins from hyperthermophilic archaea have been reported, while those from thermophilic and mesophilic archaea are largely unknown. As was pointed out, the homologous members from thermophilic and mesophilic archaea may have functions different from the hyperthermophilic members. Therefore, comparison of these homologous members can provide biophysical and structural insight into the functional diversity and thermal adaptation mechanism. The present work mainly focused on the NMR study of two Sac10b family members, Mvo10b and Mth10b, from the mesophilic and thermophilic archaea, respectively. To overcome the difficulties caused by the oligomerization and conformation heterogeneity of Mth10b, a M13T/L17Q/I20Q/P56A mutant Mth10b (Mth10bTQQA) was constructed and used together with Mvo10b for multi-dimensional NMR experiments. The resonance assignments of Mvo10b and Mth10bTQQA are reported for further structural determination which is a basis for understanding the functional diversity and their thermal adaption mechanisms.
Keywords: Archaea; Mesophilic; NMR assignments; Sac10b family; Thermal adaptation mechanism.