Figure 2.
Fig. 2. Space-filling model of B. subtilis RNase P protein.
Site-directed mutagenesis studies with the E. coli C5 protein
(18) identify residues important for holoenzyme function
(yellow); B. subtilis numbering is used. Solvent-exposed
residues in the^ central cleft (Phe^16, Phe^20), on helix B (the
RNR motif: Arg60, Asn61, Lys64, Arg65), or on strand 3
(Arg45) most likely contact RNA. Interestingly, the Arg45 His
substitution in C5 protein (B. subtilis numbering) results in a
temperature-sensitive phenotype defective in holoenzyme assembly
(18); correspondingly, this substitution must alter a critical
contact between the protein and RNA subunits. Substitution of^ a
buried residue (Phe^107, which appears as tryptophan in C5
protein) probably slightly perturbs the overall tertiary
structure, thereby compromising the overall complementarity of
protein and RNA subunits in the^ holoenzyme. Photocross-linking
studies with the B. subtilis holoenzyme^ (19) identify residues
on the protein subunit that contact the^ RNA subunit (green),
including residues at the NH[2]-terminus (Arg7) and helix C
(Arg108, Ser111) that flank helix B. These studies also
implicate Ser49 (red) and the central cleft for binding the 5
leader
sequence^ of pre-tRNA^Asp in the holoenzyme-substrate complex.
The above figure is reprinted
by permission from the AAAs:
Science
(1998,
280,
752-755)
copyright 1998.
strand 3
(Arg45) most likely contact RNA. Interestingly, the Arg45 
His
substitution in C5 protein (B. subtilis numbering) results in a
temperature-sensitive phenotype defective in holoenzyme assembly
(18); correspondingly, this substitution must alter a critical
contact between the protein and RNA subunits. Substitution of^ a
buried residue (Phe^107, which appears as tryptophan in C5
protein) probably slightly perturbs the overall tertiary
structure, thereby compromising the overall complementarity of
protein and RNA subunits in the^ holoenzyme. Photocross-linking
studies with the B. subtilis holoenzyme^ (19) identify residues
on the protein subunit that contact the^ RNA subunit (green),
including residues at the NH[2]-terminus (Arg7) and helix C
(Arg108, Ser111) that flank helix B. These studies also
implicate Ser49 (red) and the central cleft for binding the 5
leader
sequence^ of pre-tRNA^Asp in the holoenzyme-substrate complex.