Evidence for High Affinity Binding-Protein Dependent Transport Systems in Gram-Positive Bacteria and in Mycoplasma

EMBO J. 1988 Dec 1;7(12):3971-4.


Gram-negative bacteria are surrounded by two membranes. In these bacteria, a class of high affinity transport systems for concentrating substrates from the medium into the cell, involves a binding protein located between the outer and inner membranes, in the periplasmic region. These 'periplasmic binding-proteins' are thought to bind the substrate in the vicinity of the inner membrane, and to transfer it to a complex of inner membrane proteins for concentration into the cytoplasm. We report evidence leading us to propose that a Gram-positive bacterium, Streptococcus pneumoniae, and a mycoplasma, Mycoplasma hyorhinis, which are surrounded by a single membrane and have therefore no periplasmic region, possess an equivalent to the high affinity periplasmic binding-protein dependent transport systems, i.e. extra-cytoplasmic binding lipoprotein dependent transport systems. The 'binding lipoproteins' would be maintained at proximity of the inner membrane by insertion of their N-terminal glyceride-cysteine into this membrane.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / physiology*
  • Biological Transport*
  • Gram-Positive Bacteria / physiology*
  • Lipoproteins / physiology
  • Maltose / metabolism
  • Membrane Proteins / physiology*
  • Molecular Sequence Data
  • Mycoplasma / physiology*
  • Oligopeptides / metabolism


  • Bacterial Proteins
  • Lipoproteins
  • Membrane Proteins
  • Oligopeptides
  • Maltose