ROLE OF α,ε-DIAMINOPIMELIC ACID IN THE CELLULAR INTEGRITY OF ESCHERICHIA COLI

Abstract

a, e-Diaminopimelic acid was first isolated from acid hydrolyzates of Corynebacterium diphtheriae by Work (1951). Subsequent studies by Dewey and Work (1952) and by Davis (1952) have demonstrated that a, e-diaminopimelic acid (DAP) can be decarboxylated to lysine and that the path of lysine synthesis apparently involves DAP as an intermediate. Davis (1952) reported that a mutant strain of Escherichia coli (173-25), isolated by the penicillin method (Lederberg and Zinder, 1948; Davis, 1948), had an absolute requirement for DAP and a relative requirement for ilysine. Growth in the absence of lysine was slow and there appeared to be a minimum requirement of lysine for rapid growth in the presence of DAP. The work reported here is an investigation of the role of diaminopimelic acid in the nutrition of the DAP auxotroph E. coli strain 173-25. MATERIALS AND METHODS E. coli strain 173-25 (Obtained from Dr. B. Davis, New York University) was maintained at 4 C after monthly transfer on a stock agar containing: K2HHPO4, 0.3 g; yeast extract, 0.1 g; vitamin-free casein hydrolyzate, 20 ml; agar, 1.5 g; and water, 80 ml. Glucose and DAP were added aseptically to a final concentration of 8 mg/ml and 20 ,g/ml, respectively. All growth experiments were conducted in a basal medium consisting of K2HPO4, 7.0 g; KH2PO4, 3.0 g; (NH4)2SO4, 1.0 g; MgSO4-7H20, 0.1 g; lysine, 20 mg; water to 1 L. Five ml of the 2 x concentrated basal medium was dispensed in 18 by 195 mm tubes. Glucose and lysine were added to a final concentration of 8 mg/ml and 20 ,g/ml. The tubes were diluted to a total vol-' While this manuscript was in preparation Dr.

Demonstration of lanthionine as a natural constituent of the peptidoglycan of Fusobacterium nucleatum

“…It has been shown that the presence of lanthionine in the medium of Dpm auxotrophic mutans of E. coli permits growth and prevents lysis at suboptimal concentrations of Dpm (12,17). Under these conditions, however, the shape of the E. coli cells was not normal, and they tended to form spheroplasts (12).…”

LYSIS OF STREPTOCOCCUS FAECALIS

“…Lysis of other organisms can be induced by either the lack of a cell wall essential nutrient or by the action of an inhibitor of wall synthesis. The lack of diaminopimelic acid for Escherichia coli (Rhuland, 1957;McQuillen, 1958;Meadow, Hoare, and Work, 1957) is an example of the former and penicillin action (Liebermeister and Kellenberger, 1956;Lederberg, 1956;Hahn and Ciak, 1957;Shockman et al, 1958) of the latter.…”

Membrane Stability in Micrococcus Lysodeikticus and its Protoplasts

“…The presence in the M. lysodeikticus cell sheath of an autolytic enzyme system cannot be excluded (Mitchell and Moyle 1956b). In the present experiments, the bacteria are grossly deprived of nutrient and do not divide to form the osmotically fragile naked cells observed by Meadow, Hoare, and Work (1957) and Rhuland (1957) when Escherichia coli is deprived only of a single agent believed essential to the synthesis of cell wall material. The fact that aged M. lysodeikticus bacteria are almost all dumb-bell shaped could mean, on the other hand, that the processes involved in the conversion to protoplasts are intimately linked with those of cell wall production and division.…”