Nature of the receptor substance of Mycobacterium smegmatis for D4 bacteriophage adsorption

Abstract

The acetone-soluble fraction extracted from lyophilized cells of Mycobacterium smegmatis ATCC 607 inhibited D4, a species-specific phage active against M. smegmatis. Evidence is presented indicating that the D4 inhibition was caused by the phage receptor substance(s) contained in this fraction. A fraction eluted from silicic acid with chloroform-methanol (95:5, v/v) showed the strongest inhibition of D4 phage. This fraction contained sugars and amino acids, and its infrared absorption spectrum was practically identical with those of the mycoside C isolated from the other species of mycobacteria. Further fractionation revealed that the active material was a mixture of several closely related peptidoglycolipids all of which showed, more or less, the phage inhibition. One of the compounds was purified and partially characterized; it contains three different amino acids, allo-threonine, alanine, and phenylalanine, at a molar ratio of 1:1:1, and also three different deoxyhexoses, probably 6-deoxytalose, 3,4-di-o-methylrhamnose, and 2,3,4-tri-o-methylrhamnose. A tentative name of "mycoside C(sm)" is proposed for this substance which possesses a slightly different structure from the known types of mycoside C and is probably specific for the species of M. smegmatis. A fraction extracted from the D4-resistant mutant of M. smegmatis ATCC 607 by acetone and then by chloroform-methanol (95:5, v/v) showed no phage inhibition and had no sugar component. In addition, this fraction contained lysine, serine, and a small amount of both glycine and an unidentified amino acid.