Regulation of the Enzymes of Lysine Biosynthesis in Bacillus sphaericus NCTC 9602 during Vegetative Growth

Abstract

Enzymes were assayed in extracts of Bacillus sphaericus harvested late in the exponential phase from batch cultures in a minimal (acetate plus salts) medium. Aspartokinase was repressed and inhibited by threonine; lysine alone had no effect, though it increased the inhibition (but not the repression) by threonine. Aspartic fl-semialdehyde dehydrogenase was slightly repressed by lysine. Dihydrodipicolinate synthase was inhibited non-competitively by lysine, and dihydrodipicolinate reductase was partly repressed by lysine. Diaminopimelate dehydrogenase (with tetrahydrodipicolinate as substrate) was inhibited by meso-diaminopimelate. Lysine did not repress diaminopimelate decarboxylase, and only slightly inhibited this enzyme. An auxotrophic mutant that required threonine and methionine excreted lysine after growth had stopped with a limited concentration of threonine.

Comparative study of gut microbiota in wild and captive Malaysian Mahseer (Tor tambroides)

“…Lysine produced by gut microbiota was reported to be absorbed at the host's small intestines (Metges, ). Bacillus sphaericus and Bacillus megaterium were reported to have the capability to synthesize lysine (Bartlett & White, ; Ekwealor & Obeta, ).…”

Regulation of aspartokinase, aspartate semialdehyde dehydrogenase, dihydrodipicolinate synthase and dihydrodipicolinate reductase in Lactobacillus plantarum

“…In addition, the transcription of dapA1 to mRNA in L. plantarum was not repressed when the cells were grown in medium supplemented with 10 mM L-lysine (data of RT-PCR not shown). The absence of inhibition and repression of dihydrodipicolinate synthase by the end-product of the pathway was also found in Brevibacterium lactofermentum (Tosaka & Takinami, 1978), C. glutamicum (Cremer et al, 1988) and Bacillus stearothermophilus (Selli et al, 1994), but different results were found in E. coli (Yugari & Gilvarg, 1962) or Bacillus sphaericus (Barlett & White, 1986), where dihydrodipicolinate sythase was reported to be inhibited by lysine. Table 3.…”

Dihydrodipicolinate synthase from Thermotoga maritima

“…Plant enzymes are strongly inhibited by (S)-lysine (IC 50 = 0.01-0.05 mM) [20][21][22][23][24][25] and DHDPS appears to be an important metabolic step in (S)-lysine biosynthesis [18,19,26]. DHDPSs from Gram-negative bacteria are only weakly inhibited (IC 50 = 0.25-1.0 mM) [27][28][29], with (S)-lysine acting as a mixed partial inhibitor of DHDPS with respect to pyruvate and a partial noncompetitive inhibitor with respect to (S)-ASA [30]. Conversely, DHDPS enzymes from Gram-positive bacteria show little or no feedback inhibition by (S)-lysine [31][32][33][34][35][36].…”