Identification and characterization of Streptococcus pneumoniae Ffh, a homologue of SRP54 subunit of mammalian signal recognition particle

Biochemical and Biophysical Research Communications
Feng ZhengSheng-Bin Peng

Abstract

Recent studies have demonstrated that bacteria possess an essential protein translocation system similar to mammalian signal recognition particle (SRP). Here we have identified the Ffh, a homologue of the mammalian SRP54 subunit from S. pneumoniae. Ffh is a 58-kDa protein with three distinct domains: an N-terminal hydrophilic domain (N-domain), a G-domain containing GTP/GDP binding motifs, and a C-terminal methionine-rich domain (M-domain). The full-length Ffh and a truncated protein containing N and G domains (Ffh-NG) were overexpressed in E. coli and purified to homogeneity. The full-length Ffh has an intrinsic GTPase activity with k(cat) of 0.144 min(-1), and the K(m) for GTP is 10.9 microM. It is able to bind to 4.5S RNA specifically as demonstrated by gel retardation assay. The truncated Ffh-NG has approximately the same intrinsic GTPase activity to the full-length Ffh, but is unable to bind to 4.5S RNA, indicating that the NG domain is sufficient for supporting intrinsic GTP hydrolysis, and that the M domain is required for RNA binding. The interaction of S. pneumoniae Ffh with its receptor, FtsY, resulted in a 20-fold stimulation in GTP hydrolysis. The stimulation was further demonstrated to be independent of the 4.5S RN...Continue Reading

References

Nov 1, 1986·Proceedings of the National Academy of Sciences of the United States of America·U C KriegA E Johnson
Sep 25, 1984·Journal of Molecular Biology·S Brown, M J Fournier
Jun 11, 1994·Nucleic Acids Research·S AlthoffJ A Wise
Jan 1, 1994·Annual Review of Cell Biology·P Walter, A E Johnson
Feb 25, 1993·Nucleic Acids Research·T Samuelsson, M Olsson
Jan 1, 1996·Annual Review of Biochemistry·T A RapoportU Kutay
May 1, 1997·European Journal of Biochemistry·J A Newitt, H D Bernstein
Sep 7, 2001·Journal of Bacteriology·J HoskinsJ I Glass

❮ Previous
Next ❯

Citations


❮ Previous
Next ❯

Related Concepts

Related Feeds

Bacterial Pneumonia

Bacterial pneumonia is a prevalent and costly infection that is a significant cause of morbidity and mortality in patients of all ages. Here is the latest research.

Bacterial Pneumonia (ASM)

Bacterial pneumonia is a prevalent and costly infection that is a significant cause of morbidity and mortality in patients of all ages. Here is the latest research.