M. Bycroft 2026-11-05
M. Bycroft is the first-named author of a 1997 structural study of the S1 RNA-binding domain. The paper examined this protein domain from Escherichia coli polynucleotide phosphorylase using nuclear magnetic resonance. Its initial-only byline is retained here.[ref]
The resulting protein structure contained a five-stranded antiparallel beta barrel. Conserved amino acid residues and neighboring loops suggested a possible RNA-binding face. Comparing this fold with other proteins connected a small structural module with a broader family of nucleic-acid interactions.[ref]
The solution structure of the S1 RNA binding domain: a member of an ancient nucleic acid-binding fold by M. Bycroft and others. Abstract: solution structure, putative RNA-binding face and related proteins
The distinction between an observed fold and a proposed binding face is scientifically useful. Finding several conserved amino acid residues on the same exposed surface suggests an experiment: alter selected residues, then compare RNA binding while independently checking whether the protein still folds. Weaker binding after a change that also unfolds the protein would not establish a direct contact at that residue. This is an experimental interpretation of the structural hypothesis, not a report that every such test was performed in the 1997 paper.
For a simple architectural example, two proteins can each contain one S1 RNA-binding domain while having different additional protein domains. Sharing that module alone does not imply identical enzyme activity, the same RNA preference, or an equal number of active sites.
Ribosomal protein S1 2026-11-05
Ribosomal protein S1 is an RNA-binding ribosomal protein that helps many bacterial messenger RNAs engage the small ribosomal subunit for translation initiation. In Escherichia coli, S1 is a single polypeptide chain containing six related S1 RNA-binding domains. The whole protein and its repeated domain are distinct concepts; an S1 domain also occurs in proteins outside the ribosome.[ref]
Escherichia coli Ribosomal Protein S1 Unfolds Structured mRNAs Onto the Ribosome for Active Translation Initiation by Mélodie Duval and others. Introduction, E. coli S1 architecture
[ref]A 2013 study tested how S1 helps structured messages enter the decoding region. Researchers compared intact, S1-depleted and reconstituted 30S subunits, including S1 variants missing selected domains. Binding measurements and toeprinting distinguished RNA association from formation of a correctly positioned 30S initiation complex. The experiments showed different domain requirements for different messages; the first three domains were important for handling the tested structured rpsO message.[ref]
Escherichia coli Ribosomal Protein S1 Unfolds Structured mRNAs Onto the Ribosome for Active Translation Initiation by Mélodie Duval and others. Figures 3–4 and Figure S5, domain deletions and initiation-complex comparisons
For an illustrative control, suppose removing S1 reduces an initiation-associated signal for a folded message but changes a simpler message little. Restoring the signal by adding back intact S1 would support a message-dependent contribution. General loss of ribosome assembly or unequal RNA amounts could also change the readout, so they require separate checks. An RNA-binding measurement alone does not establish completed translation; a domain count alone does not specify how many functional binding sites a protein supplies.
S1 RNA-binding domain 2026-11-05
The S1 RNA-binding domain is a protein domain found in many RNA-associated proteins, named after its original identification in ribosomal protein S1. It is a reusable RNA-interaction module; its presence does not identify the entire host protein as a ribosomal component or a nuclease.[ref]
The solution structure of the S1 RNA binding domain: a member of an ancient nucleic acid-binding fold by M. Bycroft and others. Abstract: origin of the domain name and occurrence in RNA-associated proteins
A 1997 structural experiment examined the S1 domain of Escherichia coli polynucleotide phosphorylase using nuclear magnetic resonance. The resulting structure was a five-stranded antiparallel beta barrel. Conserved residues on one face and neighboring loops suggested an RNA-binding surface; that proposal distinguished an observed fold from an inferred contact function.[ref]
The solution structure of the S1 RNA binding domain: a member of an ancient nucleic acid-binding fold by M. Bycroft and others. Abstract: NMR structure and putative binding face
The 2016 RNase R study supplies a functional example. Altering residues in its S1 domain changed interactions with duplex RNA, while separate measurements examined nucleotide binding, conformational changes and degradation. A binding domain can therefore influence catalysis by positioning a substrate or stabilizing a productive state, without itself supplying all catalytic chemistry.[ref]
For an architectural counting example, a hypothetical protein with two S1 domains has two copies of that module, not automatically two RNA-cleaving active sites. Domain count, binding behavior and enzyme activity are different observations that require different evidence.