title: Contribution of aggregation-promoting factor to maintenance of cell shape in Lactobacillus gasseri 4B2.
abstract: Aggregation-promoting factor (APF) was originally described as a protein involved in the conjugation and autoaggregation of Lactobacillus gasseri 4B2, whose corresponding apf gene was cloned and sequenced. In this report, we identified and sequenced an additional apf gene located in the region upstream of the previously published one. Inactivation of both apf genes was unsuccessful, indicating that APF function may be essential for the cell. Overproduction of APF proteins caused drastic alteration in the cell shape of this strain. These cells were irregular, twisted, enlarged, and tightly bound in unbreakable clumps of chains. Down-regulation of APF synthesis was achieved by cloning of the apf2 promoter region on a high-copy-number plasmid, which recruited a putative apf activator. As a consequence, the shape of the corresponding recombinant cells was elongated (filamentous) and cell division sites were no longer visible. None of the induced changes in APF production levels was clearly correlated with modifications of the aggregation phenotype. This report shows, for the first time, that APF proteins are mainly critical for L. gasseri 4B2 cell shape maintenance.
authors.affiliation: Nestlé Research Center, Vers-chez-les-Blanc, 1000 Lausanne 26, Switzerland. ivana.jankovic@rdls.nestle.com
authors.forename: Ivana
authors.initials: I
authors.lastname: Jankovic
authors.forename: Marco
authors.initials: M
authors.lastname: Ventura
authors.forename: Valerie
authors.initials: V
authors.lastname: Meylan
authors.forename: Martine
authors.initials: M
authors.lastname: Rouvet
authors.forename: Marina
authors.initials: M
authors.lastname: Elli
authors.forename: Ralf
authors.initials: R
authors.lastname: Zink
mesh_terms: D000595:Amino Acid Sequence; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation; D020043:Genes, Essential; D007778:Lactobacillus / Q000166:cytology* / Q000378:metabolism / Q000502:physiology; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D009154:Mutation; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D015815:Cell Adhesion Molecules; C013065:cell aggregation factors