RT Journal Article SR Electronic(1) A1 LORTAL, SYLVIE A1 VAN HEIJENOORT, JEAN A1 GRUBER, KARIN A1 SLEYTR, UWE B.YR 1992 T1 S-layer of Lactobacillus helveticus ATCC 12046: isolation, chemical characterization and re-formation after extraction with lithium chloride JF Microbiology, VO 138 IS 3 SP 611 OP 618 DO https://doi.org/10.1099/00221287-138-3-611 PB Microbiology Society, SN 1465-2080, AB Summary: In a previous study, electron microscopic examinations of thin sections of Lactobacillus helveticus ATCC 12046 revealed a three-layered structure of the cell wall. The outermost component was identified as a layer of a non-glycosylated 52 kDa protein. Freeze-etched preparations of intact cells have now demonstrated that this protein layer is an oblique surface layer (S-layer) lattice (a = 4·5 nm, b = 9·6 nm, γ = 77 °) which completely covers the cell surface. Treatment with 5 m-LiCl extracted the S-layer protein from intact cells efficiently and selectively. Viability did not decrease significantly. Moreover, the S-layer reappeared when treated cells were allowed to grow again. In vitro self-assembly products obtained upon aggregation of isolated S-layer subunits exhibited the same oblique S-layer symmetry as observed on intact cells in vivo. The purified S-layer protein had a high content (44%) of hydrophobic amino acids. The N-terminal sequence was mainly composed of alanine, threonine, asparagine and aspartic acid., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-138-3-611