Role of teichuronic acid in Bacillus licheniformis: defective autolysis due to deficiency of teichuronic acid in a novobiocin-resistant mutant

Abstract

nov-12, a novobiocin-resistant mutant of Bacillus licheniformis ATCC 9945, grows as long chains of cells, a characteristic of autolytic-deficient (Lyt-) mutants. Isolated walls from nov-12 autolyzed at a rate equal to 5% of that displayed by wild-type walls, thus confirming the Lyt- phenotype. Protein-free nov-12 walls displayed marked resistance to, and also failure to bind, added autolysin solubilized from wild-type walls. Comparison of isolated cell walls revealed a deficiency in teichuronic acid in the mutant. Lesser differences were observed in walls of this strain, including a reduction in galactose, an increase in the proportion of peptidoglycan, and small quantitative differences in peptidoglycan composition though the proportions of protein and teichoic acid were similar in walls of both strains. Autolytic sensitivity was studied in walls in which protein, teichoic acid, and teichuronic acid were removed successively by selective extraction procedures. Autolysis of wild-type walls was unaffected by removal or protein or teichoic acid, but teichuronic acid removal rendered wild-type walls as insensitive to autolysis as mutant walls had been throughout. Therefore, in this mutant, deficiency in teichuronic acid alone leads to the Lyt- phenotype and, hence, activity and binding of autolysin(s) are dependent upon teichuronic acid but not teichoic acid. Also, the potential rate of autolysis of cell walls in this organism was correlated with the proportion of teichuronic acid in the wall. The possible significance of these findings with respect to control of autolysis and cell separation is discussed.

Antimicrobial Activity of 6-Oxophenolic Triterpenoids. Mode of Action againstBacillus subtilis

“…Additionally, it is known that autolysin in B. licheniformis binds only to walls that contain teichuronic acid and mutants lacking this polymer are resistant to autolysin and consequently grow in long multiseptate filaments [19] similar to those found in this study. In addition, it has previously been suggested that the ultrastructural abnormality evident in the cell walls of teichoic acid mutants may be the result of a malfunction of autolysins caused by the loss of teichoic acid as a site of localization [20].…”

Major sites of metal binding in Bacillus licheniformis walls

“…Both polymers are strongly anionic and should interact strongly with metal cations. The binding capacity of teichoic acid has been studied in detail by numerous investigators (15,20,22,26), but less work has been done on the teichuronic acid polymer (4,34,37), although it has been implicated in the control of autolysins (33). Our results with TAL walls (devoid of teichoic acid but containing teichuronic acid) suggested that they too interacted strongly with metal ions (Table 3).…”

Morphological changes associated with novobiocin resistance in Bacillus licheniformis

“…Therefore, it seemed likely that resistance to novobiocin in B. licheniformis ATCC 9945, as in S. aureus (22), may be pleiotropically associated with alterations in anionic polymers which, in this organism, give rise to the Lyt-phenotype. Data presented in an accompanying paper (29) show that this is indeed the case as cell walls of nov-12 were shown to lack teichuronic acid. Thus, novobiocin could be generally useful in the search for mutants of gram-positive organisms with alterations in cell wall composition.…”