A common ancestor for mammalian 3_1 hydroxysteroid dehydrogenase and plant dihydroflavonol reductase

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A common ancestor for mammalian 3_1 hydroxysteroid dehydrogenase and plant dihydroflavonol reductase Powered By Docstoc
					558                                                                                                                                         BJ Letters

13. Leterrier, J. F. & Eyer, J. (1987) Biochem. J. 245, 93-101
14. Leterrier, J. F., Liem, R. K. H. & Shelanski, M. L. (1982) J. Cell
    Biol. 95, 982-986
15. Weingarten, M. D., Lockwood, A. H., Hwo, S. Y. & Kirshner,
    M. W. (1975) Proc. Natl. Acad. Sci. U.S.A. 72, 1858-1862

Received 2 May 1990
                                                                                           Pregnenolone                 Progesterone

A common ancestor for mammalian 3,1-                                                   (b)           OH                                OH

hydroxysteroid dehydrogenase and plant                                           OH~         ~   ~   ~
                                                                                                                OH           0O
dihydroflavonol reductase                                                                                            ~~~~3"'O
   The enzymic complex 3,8-hydroxysteroid dehydrogenase                              OH      0                         OH    OH
(EC isomerase (EC, hereafter called
3,8-hydroxysteroid dehydrogenase, catalyses the oxidative con-                    (+ ) Dihydroquercetin
                                                                                                                   3,4-cis- Leucocyanidin
version of pregnenolone to progesterone (Fig. 1), which can be
converted to various -other steroids that function as gluco-             Fig. 1. (a) Conversion of pregnenolone to progesterone catalysed by human
corticoids, mineralocorticoids, progestins, androgens, and oes-                  3.6hydroxysteroid dehydrogenase/A5-A4 isomerase, and (b) con-
                                                                                 version of dihydroquercetin to cis-leucocyanidin catalysed by barley
trogens (Luu-The et al., 1989b). As such, this enzyme is at a key                Al protein; the C-4 ketone is reduced to an alcohol
branching point in the synthesis of steroids with central roles in
mammalian metabolism and reproductive function. Recently,
the sequences of two other steroid dehydrogenases, 17,-hyd-
roxysteroid hydrogenase (Peltoketo et al., 1988; Luu-The et al.,         protein segments. The probability of getting such a score by
1989a) and corticosteroid 1 l,-hydroxy dehydrogenase (Agarwal            chance is 6 x O-25. Bovine 3,3-hydroxysteroid dehydrogenase
et al., 1989), that are important in steroid metabolism, were            contains 372 residues. Most, but not all, of the sequence of barley
determined and found to show similarity to each other (Agarwal           (331 residues) and maize (367 residues) Al proteins have been
et al., 1989; Baker, 1990), even though they modify different            determined. The full maize Al protein sequence contains an
classes of steroids and act as different positions in the steroid        additional 12 residues at its N-terminus and 48 residues at its C-
nucleus. Evidently, gene duplication and its subsequent diver-           terminus (Rohde et al., 1987). Barley Al protein is likely to be
gence led to two proteins that are important in the synthesis            about the same length as maize Al. Thus, the region of similarity
and degradation of oestrogens, androgens and corticosteroids.            between bovine 3/3-hydroxysteroid dehydrogenase and barley
Thus, when the sequences of human and bovine 3,#-hydroxy-                dihydroflavonol reductase extends over more than half of each
steroid dehydrogenase were determined (Luu-The et al., 1989b;            protein, which may be due to this area binding the nucleotide
Zhao et al., 1989), it came as a surprise that there was no              cofactor that is important in both proteins' enzymic activity.
sequence similarity to either 17,8-hydroxysteroid dehydrogenase             The similarity between 3,l-hydroxysteroid dehydrogenase and
or lJ-hydroxysteroid dehydrogenase, even at the most distant             dihydroflavonol reductase could be due to either convergent
level. Moreover, 3/-hydroxysteroid dehydrogenase showed no               evolution or to divergence from a common ancestor. We favour
similarity to other dehydrogenases, cytochrome P-450 enzymes,            the latter possibility for several reasons. First, the proteins'
steroid isomerases, steroid binding proteins, or any other protein       ALIGN comparison score of 10.25 standard deviations has
sequence, over 10000 of which are now in the protein sequence            probability of occurring by chance of 6 x 10-25. An event with
database. This left the ancestry of 3fl-hydroxysteroid dehy-             such low probability usually is interpreted as indicating that the
drogenase unelucidated.                                                  two proteins are derived from a common ancestor. This in-
   Recently, we uncovered a clue to resolving this puzzle, after         terpretation is supported by additional evidence of similarity
completing a search of an updated version of the GenBank                 between 3,3-hydroxysteroid dehydrogenase and Al protein: these
database for sequences with similarity to 3,.-hydroxysteroid             proteins have similar oxido-reductase activity and there are
dehydrogenase. This search revealed a novel similarity between           similarities in the structure of their substrates (Fig. 1). Moreover,
3,/-hydroxysteroid dehydrogenase and barley Al protein, an               as described below, there are interesting functional similarities
NADPH-dependent reductase that converts dihydroquercetin to              between their substrates, flavonoids and steroids, which may
 cis-leucocyanidin (Fig. 1) in barley (Rohde et al., 1987). Homo-        shed light on the origins of intercellular communication in
 logous dihydroflavonol reductases in maize (Schwarz-Sommer              vertebrates (Baker, 1990).
et al., 1987) and snapdragons (Coen et al., 1986) are used to form          Although it would not appear, at first glance, that the flavonoid
pigments from flavonoid precursors (Reddy et al., 1987). The             precursors of plant pigments have any biological function in
sequence similarity between bovine /1-hydroxysteroid dehydro-            common with steroids in vertebrates, in fact, like steroids, there
genase and residues 3-232 of barley Al protein is sufficiently           is evidence that flavonoids can regulate gene transcription in a
strong to suggest that these mammalian mammalian and plant               variety of organisms. The best characterized examples are in
enzymes are derived from a common ancestor.                              bacteria that interact with plants (Djordjevic et al., 1987; Firmin
   Fig. 2 shows the alignment of residues 8-236 of bovine 3,3-           et al., 1986; Long, 1989; Peters et al., 1986; Stachel et al., 1985).
hydroxysteroid dehydrogenase and residues 3-232 of barley Al             The dependence of flavonoid biological activity in intercellular
protein. There are 55 matches out of a possible 227 matches              communication between plants and rhizobia on flavonoid struc-
(24 %) and 29 conservative replacements (13 %), with five gaps           ture has similarities to that of steroids in vertebrates. Thus, the
added by the computer to maximize the alignment between the              addition or removal of a hydroxyl group from a flavonoid, or the
two proteins. The ALIGN (Dayhoff et al., 1983) comparison                oxidation of a hydroxyl group to a ketone, can have important
score between these proteins is 10.25 standard deviations higher         effects on a flavonoid's (i) biological potency and (ii) selectivity
than that of 1 000 comparisons of randomized sequences of these          for different rhizobia (Firmin et al., 1986). Different plant
 BJ Letters                                                                                                                                           559
                         Bovine 3l-OH        8   V T G G G G F L G Q R I I C L L V E E K D L Q E
                         Barley Flavonol     3   V T G A S G Y I A S W L V K L L L H - R G Y T V
                                                 V T G     G * *       * *   L L *

                         Bovine 3i-OH        I R V L D K V F R P E V R E E F S K L Q S - K I K L
                         Barley Flavonol     R A T V R D T A D P K K T L H L Q A L E G A K E R L
                                                   0           P                 L *     K   * L

                         Bovine 3P-OH        T L     L E G D I L D E Q C L K G A C Q G T S V V I H T
                         Barley Flavonol     H L     F K A S L L E E G T F D S A I A G C D C V F H T
                                                 L           0 L * E           A     G       V   H T
                         Bovine 3P-OH        A S     V I D V R N A V P R E T I M N V N V K G T Q L L
                         Barley Flavonol     A S     P F Y H N V K D P K A E L L D P A V N G T L N V
                                             A S                              r    s         0              G* T

                         Bovine   30-OH      L E A C V Q A S           V P V F I          H T S T I E V A G P N S Y
                         Barley Flavonol     L R S C K K A S           I K R V I          V T S S M A A V A Y N G K
                                             L     C     A S           *       I            T S               N

                         Bovine   30-OH      R E I I Q D G R E E E H H E S                       A W S S P      Y P Y S K K
                         Barley Flavonol     P R T P D V V V D E T W F S S                       A E V C E      K N K Q W Y
                                                     *       * E         S                       A

                         Bovine 3p-.OH       L A E K A V L G A N G W A L K N G G T L Y T C A L R
                         Barley Flavonol     V L S K T L A E E A A W K F A K D N G L E I I T I N
                                             *     K   *           W               L         0

                         Bovine 3f-OH        P M Y I Y G E G - S P F L S A Y M H G A L N - N N G
                         Barley Flavonol     P T M V I G P L L Q P T L N T S A E A I L K F I N G
                                             p     *   G         P   L               L       N G
                         Bovine 3P-OH        I L T N H C K F S R V N P V YV G N V A W A H I                                  L A
                         Barley Flavonol     S S S T Y A N F C - F G W V N V K D V A L A H I                                 L A
                                                 *         F            V  V     V A   A H I                                 L A
Fig. 2. Alignment of residues 8-236 of bovine 3/hydroxysteroid dehydrogenase and residues 3-232 of barley dihydroflavonol reductase
   Identities are shown below the alignment; an asterisk denotes conservative replacements. Out of 227 possible matches there are 55 (24 %o) identities
   and 29 (13 %) conservative replacements. An ALIGN analysis of these sequences, with a gap penalty of 10, yields a score that is 10.25 standard
   deviations higher than that obtained with 1000 comparisons of randomized sequences of these segments. The probability of getting such a score
   by chance is 6 x 10 25. An ALIGN analysis of the maize Al and bovine 3,8-hydroxysteroid dehydrogenase yields a score of 9.7 standard deviations
   (P = 10"24). An ALIGN analysis of human 3fl-hydroxysteroid dehydrogenase with barley Al protein yields a score of 9.85 standard deviations.

flavonoids have chemotactic activity towards specific rhizobia.                   Baker, M. E. (1990) FASEB J. 4, 222-226
Like steroids, flavonoid potency and target specificity can be con-               Coen, E. S., Carpenter, R. & Martin, C. (1986) Cell 47, 285-296
trolled by enzymic modification of functional groups. Moreover,                   Dayhoff, M. O., Barker, W. C. & Hunt, L. T. (1983) Methods Enzymol.
some flavonoids can inhibit gene transcription in Rhizobium,                        91, 524-545
when in competition with an inducer (Djordjevic et al., 1987;                     Djordjevic, M. A., Redmond, J. W., Batley, M. & Rolfe, B. G. (1987)
                                                                                     EMBO J. 6, 1173-1179
Firmin et al., 1986), thus acting as antagonists, a property that                 Firmin, J. L., Wilson, K. E., Rossen L. & Johnston, A. W. B. (1986)
is important in steroid biology. Interestingly, flavonoids bind to                  Nature (London) 324, 90-92
oestrogen receptors and have oestrogenic actions in mammals                       Long, S. R. (1989) Cell 56, 203-214
(Martin et al., 1978). Moreover, the isoflavonid quercetin has                    Luu-The, V., Lachance, Y., Labrie, C., Leblanc, G., Thomas, J. L.,
anti-oestrogen-like actions when binding to type II binding sites                    Strickler, R. C. & Labrie, F. (1989a) Mol. Endocrinol. 3, 1310-1312
in rat uterus (Markaverich et al., 1988). These parallels between                 Luu-The, V., Labrie, C., Zhao, H. F., Couet, J., Lachance, Y., Simard,
                                                                                    J., Leblanc, G., Cote, J., Berube D., Gagne, R. & Labrie, F. (1989b)
flavonoids and steroids support the notion of a common ancestry                      Mol. Endocrinol. 3, 1301-1309
for 3fl-hydroxysteroid dehydrogenase and dihydroflavonol re-                      Markaverich, B. M., Roberts, R. R., Alejandro, M. A., Johnson, G. A.,
ductase inferred from their sequence similarity.                                     Middleitch, B. S. & Clark, J. H. (1988) J. Steroid Biochem. 30, 71-78
                                                                                  Martin, P. M., Horwitz, K. B., Ryan, D. S. & McGuire, W. L. (1978)
   M.E.B. is a Visiting Scientist in the laboratory of Dr. Joseph J. Salvo           Endocrinology (Baltimore) 103, 1860-1867
in the Biological Sciences Laboratory, GE Research and Development,               Peltoketo, H., Isomaa, V., Maentausta, 0. & Vihko, R. (1988) FEBS
whose support in gratefully acknowledged. V.L.T., J.S. and F.L. are                  Lett. 239, 73-77
grateful to the Medical Research Council of Canada for its financial              Peters, N. K., Frost J. W. & Long S. R. (1986) Science 233, 977-980
support.                                                                          Reddy, A. R., Britsch, L., Salamini, F., Saedler H. & Rohde, W. (1987)
                                                                                     Plant Sci. 52, 7-13
Michael E. BAKER,* Van LUU-THE,t                                                  Rohde, W., Barzen, E., Marocco, A., Schwarz-Sommer, Z., Saedler, H.
Jacques SIMARDt and Fernand LABRIEt                                                 & Salamini, F. (1987) Barley Genet. 5, 533-541
* Department of Medicine M-023, University of California, San Diego,              Schwarz-Sommer, Z., Shepherd, N., Tacke, E., Gierl, A., Rohde, W.,
La Jolla, CA 92093, U.S.A., and t Department of Molecular Endo-
                                                                                     Leclerq, L., Mattes, M., Berndtgen, R., Peterson, P. A. & Saedler, H.
                                                                                     (1987) EMBO J. 6, 287-294
crinology, CHUL Research Centre and Laval University, 2705 Laurier                Stachel, S. E., Messens, E., Van Montagu, M. & Zambryski, P. (1985)
Boulevard, Quebec GIV 4G2, Canada                                                   Nature (London) 318, 624-629
Agarwal, A. K., Mondor C., Eckstein, B. & White, P. C. (1989) J. Biol.            Zhao, H.-F., Simard, J., Labrie, C., Breton, N., Rheaume, E., Luu-The,
   Chem. 264, 18939-18943                                                           V. & Labrie, F. (1989) FEBS Lett. 259, 153-157

Received 21 February 1990

Vol. 269

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