Evidence that the N-terminal part of the S-layer protein from Bacillus stearothermophilus PV72/p2 recognizes a secondary cell wall polymer.
The S-layer of Bacillus stearothermophilus PV72/p2 shows oblique lattice symmetry and is composed of identical protein subunits with a molecular weight of 97,000. The isolated S-layer subunits could bind and recrystallize into the oblique lattice on native peptidoglycan-containing sacculi which consist of peptidoglycan of the A1gamma chemotype and a secondary cell wall polymer with an estimated molecular weight of 24,000. The secondary cell wall polymer could be completely extracted from peptidoglycan-containing sacculi with 48% HF, indicating the presence of phosphodiester linkages between the polymer chains and the peptidoglycan backbone. The cell wall polymer was composed mainly of GlcNAc and ManNAc in a molar ratio of 4:1, constituted about 20% of the peptidoglycan-containing sacculus dry weight, and was also detected in the fraction of the S-layer self-assembly products. Extraction experiments and recrystallization of the whole S-layer protein and proteolytic cleavage fragments confirmed that the secondary cell wall polymer is responsible for anchoring the S-layer subunits by the N-terminal part to the peptidoglycan-containing sacculi. In addition to this binding function, the cell wall polymer was found to influence the in vitro self-assembly of the guanidinium hydrochloride-extracted S-layer protein. Chemical modification studies further showed that the secondary cell wall polymer does not contribute significant free amino or carboxylate groups to the peptidoglycan-containing sacculi.
Ries
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W
Zentrum für Ultrastrukturforschung und Ludwig Boltzmann-Institut für Molekulare Nanotechnologie, Universität für Bodenkultur, Vienna, Austria.
Hotzy
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C
Schocher
I
I
Sleytr
U B
UB
Sára
M
M
D018528:ATP-Binding Cassette Transporters / Q000502:physiology; D027322:Amino Acid Transport System X-AG; D001426:Bacterial Proteins / Q000032:analysis; D002473:Cell Wall / Q000737:chemistry; D003460:Crystallization; D001411:Geobacillus stearothermophilus / Q000737:chemistry*; D010457:Peptidoglycan / Q000032:analysis
D018528:ATP-Binding Cassette Transporters; D027322:Amino Acid Transport System X-AG; D001426:Bacterial Proteins; D010457:Peptidoglycan