Functional role of putative critical residues in Mycobacterium tuberculosis RNase P protein.

RNase P is involved in processing the 5' end of pre-tRNA molecules. Bacterial RNase P contains a catalytic RNA subunit and a protein subunit. In this study, we have analyzed the residues in RNase P protein of M.

Denatured states of yeast cytochrome c induced by heat and guanidinium chloride are structurally and thermodynamically different.

A sequence alignment of mammalian cytochromes c with yeast iso-1-cytochrome c (y-cyt-c) shows that the yeast protein contains five extra N-terminal residues. We have been interested in understanding the question: What is the role of these five extra N-terminal residues in folding and stability of the protein? To answer this question we have prepared five deletants of y-cyt-c by sequentially removing these extra residues. During our studies on the wild type (WT) protein and its deletants, we observed that the amount of secondary structure in the guanidinium chloride (GdmCl)-induced denatured (D) state of each protein is different from that of the heat-induced denatured (H) state.

Influence of Conformation of M. tuberculosis RNase P Protein Subunit on Its Function.

RNase P is an essential enzyme that processes 5' end leader sequence of pre-tRNA to generate mature tRNA. The bacterial RNase Ps contain a RNA subunit and one protein subunit, where the RNA subunit contains the catalytic activity. The protein subunit which lacks any catalytic activity, relaxes the ionic requirements for holoenzyme reaction and is indispensable for pre-tRNA cleavage in vivo.

Characterization of pre-molten globule state of yeast iso-1-cytochrome c and its deletants at pH 6.0 and 25 °C.

To understand the role of five extra N-terminal residues, we prepared wild type (WT) yeast iso-1-cytochrome c (y-cyt-c) and its deletants by subsequently deleting these residues. Denaturation of all these proteins induced by LiCl was followed by observing changes in molar absorption coefficient at 405 nm (Δɛ405), the mean residue ellipticity at 222 nm ([θ]222), and the difference mean residue ellipticity at 409 nm (Δ[θ]409) near physiological pH and temperature (pH 6.0 and 25 °C).

In vitro and in silico studies of urea-induced denaturation of yeast iso-1-cytochrome c and its deletants at pH 6.0 and 25 °C.

Yeast iso-1-cytochrome c (y-cyt-c) has five extra residues at N-terminus in comparison to the horse cytochrome c. These residues are numbered as -5 to -1. Here, these extra residues are sequentially removed from y-cyt-c to establish their role in folding and stability of the protein.

Effect of sequential deletion of extra N-terminal residues on the structure and stability of yeast iso-1-cytochrome-c.

A sequence alignment of yeast cytochrome-c (y-cyt-c) with mammalian cyts-c shows that the yeast protein has a five residue long N-terminal extension. A question arises: Does this N-terminal extension play any roles in the stability, structure, and folding of the yeast protein? To answer this question, in silico and in vitro studies were carried out on the wild type (WT) protein and its five deletants (Δ(-5/-5), Δ(-5/-4), Δ(-5/-3), Δ(-5/-2), and Δ(-5/-1) where Δ denotes the deletion and the numbers refer to the residues deleted, e.g.