Functional replacement of the hemolysin A transport signal by a different primary sequence.

Abstract

Secretion of the 107-kDa hemolysin A (HlyA) from Escherichia coli is mediated by the membrane proteins hemolysin B and hemolysin D. Hemolysin B is a member of the so-called ATP binding cassette transporter superfamily, which includes the multidrug resistance P-glycoprotein, the cystic fibrosis CFTR protein, and the major histocompatibility complex-associated transporter of antigenic peptides. Recognition of HlyA by the hemolysin B/D transporter is dependent on a signal sequence mapped to the C-terminal 50 or so amino acids of the HlyA molecule. We show that the C-terminal 70 amino acids of leukotoxin from Pasteurella hemolytica can substitute functionally for the HlyA signal sequence. This 70-amino acid sequence contains no primary sequence similarity to the HlyA signal sequence; however, structural motifs of helix-turn-helix followed by strand-loop-strand can be deduced for both sequences. We also demonstrate by site-directed mutagenesis that changes to these predicted motifs affect transport function. It thus appears that the transport signal of HlyA may be defined by a higher-order structure and that the hemolysin transporter may recognize a much wider diversity of primary sequences than previously anticipated. This finding may have implications for understanding the basis of substrate specificity of other ATP binding cassette transporters.

• Authors: F Zhang, D I Greig, V Ling
• Journal: Proceedings of the National Academy of Sciences of the United States of America (Proc Natl Acad Sci U S A) Vol. 90 Issue 9 Pg. 4211-5 (May 01 1993) ISSN: 0027-8424 [Print] United States
• PMID: 8483936 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Bacterial Proteins
• Bacterial Toxins
• Carrier Proteins
• Escherichia coli Proteins
• Exotoxins
• Hemolysin Proteins
• Hlya protein, E coli
• Oligodeoxyribonucleotides
• Protein Sorting Signals
• Recombinant Fusion Proteins
• leukotoxin
• Adenosine Triphosphate

Topics

• Adenosine Triphosphate (metabolism)
• Amino Acid Sequence
• Animals
• Bacterial Proteins (genetics, metabolism, toxicity)
• Bacterial Toxins (genetics)
• Base Sequence
• Carrier Proteins (metabolism)
• Erythrocytes (drug effects, physiology)
• Escherichia coli (genetics)
• Escherichia coli Proteins
• Exotoxins (genetics)
• Genes, Bacterial
• Hemolysin Proteins (genetics)
• Hemolysis
• In Vitro Techniques
• Mannheimia haemolytica (genetics)
• Molecular Sequence Data
• Mutagenesis, Insertional
• Oligodeoxyribonucleotides
• Plasmids
• Polymerase Chain Reaction (methods)
• Protein Sorting Signals (genetics, metabolism)
• Protein Structure, Secondary
• Recombinant Fusion Proteins (metabolism)
• Restriction Mapping
• Sequence Homology, Amino Acid
• Sheep