Linked Life Data

8057378

Source:http://linkedlifedata.com/resource/pubmed/id/8057378

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1994-9-15
pubmed:abstractText
E. coli phages of the T4 family (T4, TuIa, TuIb) recognize their cellular receptors with a C-terminal region of protein 37. This protein, common to all three phages, is present as a dimer located at the distal part of the long tail fibers and possesses a C-terminal domain consisting of 40 to 70 highly conserved C-terminal residues, followed by a variable region of 50 to 80 residues which is again followed by a highly conserved area. Protein 38, not being a component of the mature virion, is required for dimerization of protein 37; this represents a non-covalent association of a structural protein. Seven host range mutants of TuIa or TuIb were analyzed which were able to use proteinaceous receptors other than those recognized by their parents. All had suffered amino acid substitutions within the variable region. It is concluded that in all probability it is this region which interacts directly with the cellular receptors. Conditional mutants of T4 are known which, when propagated at the non-permissive temperature (42 degrees C), yield phage of normal morphology but these are more or less unable to adsorb to cells. The causative amino acid substitutions were found both downstream and upstream from the variable area. Distortion of it in the mutants could suggest a "snap-back" conformation of the tail fiber; the conserved C-terminal region may fold back and expose the variable region as a loop at the tip of the fiber. One of the phage mutants (L93), when grown at the permissive temperature, had lost the ability to use the OmpC porin (a receptor for T4) as a receptor. A secondary mutant, able to do so, was isolated. An additional mutation, leading to one amino acid substitution, had occurred in gene 38. This mutant gene acted in trans and caused a much enhanced temperature-sensitivity of infectivity without conferring temperature-sensitivity per se, i.e. the mutant protein 38 apparently altered the conformation of the receptor-recognizing area of the dimer of protein 37. A gene from phage lambda, about 40% identical to gene 38 of T4, complements gene 38 amber mutants. The corresponding protein also restored the ability of L93 to recognize OmpC but did not cause any such temperature-sensitivity. Hence, protein 38, classifying as a chaperone, appears to act instructively in conveying steric information to the target polypeptide.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0022-2836
pubmed:author
pubmed:issnType
Print
pubmed:day
26
pubmed:volume
241
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
524-33
pubmed:dateRevised
2000-12-18
pubmed:meshHeading
pubmed:year
1994
pubmed:articleTitle
Determinants of receptor specificity of coliphages of the T4 family. A chaperone alters the host range.
pubmed:affiliation
Max-Planck-Institut für Biologie, Tübingen, Germany.
pubmed:publicationType
Journal Article