TABLE 6.
Hydrolysis of Nod factors by chitinases and related enzymesa
| Enzyme | Plant isozymesb | Nod factors used as substratesbc | Acylated products in hydrolysatebd | Reference(s) |
|---|---|---|---|---|
| Chitinase class I | Ms, Pv, Vs, Nt | NodRm-V(C16:2, S) | III | 241, 258 |
| Ms, Vs | NodRm-V(C16:2) | IV, III | 258 | |
| Ms, Pv, Vs, Nt | NodRm-IV(C16:2, S) | None | 241, 258 | |
| Ms, Pv, Vs, Nt | NodRm-IV(C16:2) | III | 241, 258 | |
| Vu | NodNGR-V(AcMeFuc) | Unknown structures | 259 | |
| Vu | NodNGR-V(SMeFuc) | Unknown structures | 259 | |
| Ps, Pv, Vu | NodNGR-V(MeFuc) | Unknown structures | 259 | |
| Nt | NodRm-IV(Ac, C16:2) | None | 241 | |
| Nt | NodRlv-V(Ac, C18:4) | AcIV, AcIII | Ovtsyna et al., submitted | |
| Nt | NodRlv-V(Ac, C18:4, Fuc) | AcIII | Ovtsyna et al., submitted | |
| Nt | NodRlv-IV(Ac, C18:4) | None | Ovtsyna et al., submitted | |
| Nt | NodRlv-IV(Ac, C18:4, Fuc) | None | Ovtsyna et al., submitted | |
| Chitinase class II | Nt | NodRm-V(C16:2, S) | III | 241 |
| Nt | NodRm-IV(C16:2, S) | None | 241 | |
| Nt | NodRm-IV(C16:2) | III | 241 | |
| Chitinase class III | Ca, Bv, Nt | NodRm-V(C16:2, S) | III, II | 241 |
| Ca, Bv, Nt | NodRm-IV(C16:2, S) | II | 241 | |
| Ca, Bv, Nt | NodRm-IV(C16:2) | III, II | 241 | |
| Sr | NodAc factors | Unknown structures | 103 | |
| Nt | NodRm-IV(Ac, C16:2, S) | None | 241 | |
| Nt | NodRm-V(Ac, C16:2, S) | AcIII | 241 | |
| Nt | NodRlv-V(Ac, C18:4) | AcIV, AcIII | Ovtsyna et al., submitted | |
| Nt | NodRlv-V(Ac, C18:4, Fuc) | AcIII | Ovtsyna et al., submitted | |
| Nt | NodRlv-IV(Ac, C18:4) | AcIII | Ovtsyna et al., submitted | |
| Nt | NodRlv-IV(Ac, C18:4, Fuc) | None | Ovtsyna et al., submitted | |
| Chitinase class IV | Bv, Dc | NodRm-V(C16:2, S) | III | 241 |
| Bv, Dc | NodRm-IV(C16:2, S) | None | 241 | |
| Bv, Dc | NodRm-IV(C16:2) | III | 241 | |
| Chitinase class V | Nt | NodRm-V(C16:2, S) | III | 241 |
| Nt | NodRm-IV(C16:2, S) | None | 241 | |
| Nt | NodRm-IV(C16:2) | III | 241 | |
| Chitinase class VI | Nt | NodRm-V(C16:2, S) | III | 241 |
| Nt | NodRm-IV(C16:2, S) | None | 241 | |
| Nt | NodRm-IV(C16:2) | III | 241 | |
| Novel chitinase/lysozyme | Ms | NodRm-V(C16:2, S) | III | 179 |
| Ms | NodRm-IV(C16:2, S) | III | 179 | |
| Ms | NodRm-IV(C16:2) | III | 179 | |
| Ms | NodRm-IV(Ac, C16:2, S) | AcIII | 179 | |
| Nod factor hydrolase | Ms | NodRm-V(C16:2, S) | II | 258, 260 |
| Ms | NodRm-V(C16:2) | II | 258 | |
| Ms | NodRm-IV(C16:2, S) | II | 258, 260 | |
| Ms | NodRm-IV(C16:2) | II | 258, 260 | |
| Ms | NodRm-IV(Ac, C16:2, S) | AcII | 260 | |
| Ms | NodRm-V(Ac, C16:2, S) | AcII | 260 | |
| Roots | Ms, Vs | NodRm-V(C16:2, S) | III, II | 258, 260 |
| Ms, Vs | NodRm-V(C16:2) | IV, III, II | 258 | |
| Ms, Vs | NodRm-IV(C16:2, S) | II | 258, 260 | |
| Ms, Vs | NodRm-IV(C16:2) | III, II | 258 | |
| Ms | NodRm-IV(C16:0, S) | II | 258 | |
| Ms, Ps, Vs | NodRlv-V(Ac, C18:4) | AcIV, AcIII, AcII | 97, 118 | |
| Vs | NodRlv-IV(Ac, C18:4) | AcIII, AcII | 118 | |
| Vs | NodRlv-V(Ac, C18:0) | AcIV, AcIII, AcII | 118 | |
| Sr | NodAc factors | Unknown structures | 103 |
Purified enzymes (as well as whole roots) of both legumes (bold) and nonlegumes were incubated with Nod factors, and the reaction products were examined for the presence of acylated chitin fragments.
Abbreviations are as follows. Hydrolases were isolated from the following legumes: Cicer arietinum (Ca), Medicago sativa (Ms), Phaseolus vulgaris (Pv), Pisum sativum (Ps), Sesbania rostrata (Sr), Vicia sativa (Vs), and Vigna unguiculata (Vu) and the nonlegumes Beta vulgaris (Bv), Daucus carota (Dc), and Nicotiana tabacum (Nt). Chemical groups are abbreviated as follows: acetyl (Ac), fucosyl (Fuc), methyl (Me), sulfate (S), methylfucose (MeFuc), acetylated methylfucose (AcMeFuc), sulfated methylfucose (SMeFuc).
Nod factors were purified from A. caulinodans (NodAc), R. leguminosarum bv. viciae (NodRlv), Rhizobium sp. strain NGR234 (NodNGR), and R. meliloti (NodRm). Details of their structure, such as the presence of certain baroque decorations (for abbreviations, see footnote b), the length of the acyl chain, and the number of double bonds, are shown in brackets. Tetramers and pentamers of N-acetylglucosamine are marked as IV and V, respectively. The nonsulfated NodRm factors and fucosylated NodRlv factors are derivatives of the wild type obtained by desulfation and fucosylation with NodZ, respectively. NodRm-IV(C16:0, S) was prepared from NodRm-IV(C16:2, S) by catalytic reduction.
Acylated products were separated from the substrate by reverse-phase high-pressure liquid chromatography (179, 241, 258, 260; A. O. Ovtsyna, M. Schultze, I. A. Tikhonovich, H. P. Spaink, É. Kondorosi, Á. Kondorosi, and C. Staehelin, submitted for publication) and thin-layer chromatography (97, 103, 118, 258). Abbreviations: lipotetrasaccharide (IV); lipotrisaccharide (III); lipodisaccharide (II); O-acetylated lipotetrasaccharide (AcIV); O-acetylated lipotrisaccharide (AcIII); O-acetylated lipodisaccharide (AcII); Nod factors resistant to hydrolysis by the given enzyme (None).