Figure 1.
Figure 1. Components of the S15−rRNA complex. a, Sequence
of the Thermus thermophilus S15 protein^17. Colored residues are
>80% conserved among 23 bacterial sequences (green) and
additionally conserved among 55 homologous sequences from
plastids, Archaea and Eukarya (red). Amino acids that interact
with the rRNA fragment are underlined, and the four -helices
deduced from the crystallographic structure are indicated. b,
Schematic of tertiary structure of the 57 nt RNA corresponding
to nucleotides 584−590/649−667/739−757 of E. coli rRNA as
determined by comparative sequence analysis, and contacts with
protein. Nucleotides within the UUCG loops capping helices 21
and 22 are in italics. Bases in red are >95% conserved in 6,000
prokaryotic sequences. Ribose rings in black are in a C2'-endo
conformation, stacking is shown by hatched lines, and water
molecules are indicated by W. Two alternative conformations of
G664 are shown. Nucleotide C748 is not well defined. Conserved
amino acid residues are colored as in (a), and their contacts
with RNA backbone (phosphate group or 2'-OH) or functional
groups of bases are indicated. Contacts are with amino acid side
chains, with the single exception of Gly 22, which interacts
through the backbone carbonyl.
-helices
deduced from the crystallographic structure are indicated. b,
Schematic of tertiary structure of the 57 nt RNA corresponding
to nucleotides 584−590/649−667/739−757 of E. coli rRNA as
determined by comparative sequence analysis, and contacts with
protein. Nucleotides within the UUCG loops capping helices 21
and 22 are in italics. Bases in red are >95% conserved in 
6,000
prokaryotic sequences. Ribose rings in black are in a C2'-endo
conformation, stacking is shown by hatched lines, and water
molecules are indicated by W. Two alternative conformations of
G664 are shown. Nucleotide C748 is not well defined. Conserved
amino acid residues are colored as in (a), and their contacts
with RNA backbone (phosphate group or 2'-OH) or functional
groups of bases are indicated. Contacts are with amino acid side
chains, with the single exception of Gly 22, which interacts
through the backbone carbonyl.