Vol.

176,

May

15, 1991

No.

3, 1991

BIOCHEMICAL

BIOPHYSICAL

RESEARCH

COMMUNICATIONS Pages

REGULATION

OF GUANYLATE CYCLASE BY A GUANINE NUCLEOTIDE PROTEIN, Ga2, IN DICTYOSTELIUM DISCOIDEUM

MASAKAZU

OYAMAl ’ 2 ’ * , KOU KUBOTA2

of

‘Department

Botany,

‘Department Himeji Institute

Received

AND

February

of

and KOJI

Faculty of Science, Kyoto 606 Japan Life Science, of Technology; Hyogo 671-22,

BINDING

OKAMOTO’

Kyoto

Faculty Shosha Japan

1245-l 249

University,

of Science, 2167, Himeji

19, 1991

Binding of cyclic AMP (CAMP) to the cell surface receptor induces a transient activation of guanylate cyclase in Dictyostelium discoideum. A frigid mutant (HC85) which lacks Ga 3 a guanine nucleotide binding protein, does not respond to E.AMP. We found that 2,3-dimercapto-1-propanol (BAL) induced a continuous activation both in the frigid and in its parents. the BAL-induced continuous activation of guanylate Therefore, We also found that CAMP enhanced cyclase is independent of Ga2. the BAL-induced continuous activation in the frigid mutant. This result suggests that an unidentified signal transduction mechanism from the CAMP-receptor besides the one involving G~y2 plays a role in the enhancement of activation. Lastly, we found that the BAL-induced continuous activation was terminated by CAMP but not in the frigid mutant. Therefore, in the parental strain, the CAMP-induced suppression on the BAL-induced continuous activation is mediated through Gcy2. 0 1991 Academic Press, Inc.

Starvation Dictyostelium intrinsic cells signal induce

triggers

C1,2,31 for

development

discoideum. agonist, binds and guanylate

a transient

*

induces activation should Himeji Japan.

Abbreviations i ne-3 ‘:5’-cyclic cyclic monophosphate;

used:

in

signal

These of

two

guanylate

be addressed Institute

the

cellular

been known receptors

activation

cyclase.

To whom correspondence Faculty of Science, Himej i Hyogo 671-22, adenos

to

It has specific

slime

mold,

that CAMP, an on the starved and inactivation

intracellular cyclase

at Department of Technology,

signals C4,51. of

Life Shosha

Science, 2167,

CAMP, 2,3-dimercapto-1-propanol; BAL, monophosphate; cGMP, guanosine-3’:5’Gor2, guanine nucleotide binding proteinCY2. 0006-291X/91 $1.50 1245

Copyright 0 1991 by Academic Press, Inc. All rights of reproduction in any form reserved.

Vol.

176,

No.

(submitted)

Oyama

induces

BIOCHEMICAL

3, 1991

continuous It NC4.

strain, difference in BAL (continuous). enhances suppresses

found

activation should be

the

BIOPHYSICAL

CAMP-induced BAL-induced the NC4. Thus,

probably

a

through

the

COMMUNICATIONS

reducing

of guanylate cyclase emphasized that there

reagent, in

a wild type is a marked

between CAMP (transient) further showed that

transient continuous effects of

the

RESEARCH

BAL,

that

mode of activation Oyama (submitted)

the

cyclase in each other

AND

and BAL

activation although CAMP activation of guanylate CAMP and BAL interact with

intracellular

signal

transduction

pathwayts). It

has

protein receptor fact, Coukell

been

reported

which is mediates a

frigid &

C81 and

2 gene C61 cannot stimulation C91 guanylate

thought to the activation

mutant

al.

cyclase

an only defect We recently

later

activate although

cyclase, in the frigid

induces activation of of adenylate cyclase

advantage actions

of the specific of BAL and

loss CAMP

of

isolated

a deletion

the

we

investigated

the

frigid mutant transduction

to clarify the in the regulation

role of

other

mutant guanylate in the

is

effects

frigid

to

thought

GK

CAMP and to

be

in HC85 161. of G