Differentiation-inducing factor from the slime mould Dictyostelium discoideum and its analogues. Synthesis, structure and biological activity.
Previous work has led to the identification of a novel class of effector molecules [DIFs (differentiation-inducing factors) 1-3] released from the slime mould Dictyostelium discoideum. These substances induce stalk-cell differentiation in Dictyostelium discoideum and are thought to act as morphogens in the generation of the prestalk/prespore pattern during development. The DIFs are phenylalkan-1-ones, with chloro, hydroxy and methoxy substitution on the benzene ring. DIFs 1-3 and a number of their analogues have been synthesized by using a simple two-step procedure, and each analogue has been characterized by m.s., u.v. and n.m.r. spectroscopy. The crystal structure of synthetic DIF-1 [1-(3,5-dichloro-2,6-dihydroxy-4-methoxyphenyl)hexan-1-one, was investigated. The specific biological activity of each analogue was determined in a bioassay, where isolated Dictyostelium amoebae are induced to differentiate into stalk cells. The major biologically active substance, DIF-1, caused 50% stalk-cell differentiation at 1.8 x 10(-10) M; the C4 alkyl homologue (DIF-2) and C6 homologue possessed 40 and 16% of the activity of DIF-1 respectively. Further increase or decrease in the alkyl chain length resulted in a marked decrease in specific activity. The pattern of substitution on the benzene ring is a major determinant of bioactivity, since the specific activities of the 2,4-dihydroxy-6-methoxy and trihydroxy analogues were less than 1% of that of DIF-1. Substitution of bromine in DIF-1 had little effect on bioactivity; in contrast the activity of monochloro-DIF-1 (DIF-3) was diminished. There was no evidence for antagonism or synergy between DIF-1 and any of its analogues. This series of analogues will facilitate further studies in the biological effects and mode of action of DIF-1.
Masento
M S
MS
Department of Biochemistry, Imperial College of Science and Technology, London, U.K.
Morris
H R
HR
Taylor
G W
GW
Johnson
S J
SJ
Skapski
A C
AC
Kay
R R
RR
D002454:Cell Differentiation; D002851:Chromatography, High Pressure Liquid; D004023:Dictyostelium / Q000378:metabolism*; D006588:Hexanones / Q000138:chemical synthesis / Q000378:metabolism*; D007659:Ketones / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008958:Models, Molecular; D010422:Pentanones / Q000138:chemical synthesis / Q000378:metabolism*
D006588:Hexanones; D007659:Ketones; D010422:Pentanones; C053433:1-((3,5-dichloro)-2,6-dihydroxy-4-methoxyphenyl)-1-hexanone; C055365:1-(3,5-dichloro-2,6-dihydroxy-4-methoxyphenyl-)-1-pentanone; C055364:1-(3-chloro-2,6-dihydroxy-4-methoxyphenyl)-1-hexanone