Aldehyde dehydrogenases for oligo-isoprene aldehyde oxidation in Rhodococcus sp. RDE2
- 1Department of Materials Science and Bioengineering, Nagaoka University of Technology, Nagaoka, Niigata 940-2188 Japan
- 2Department of Bioresources Engineering, National Institute of Technology, Okinawa College, Nago, Okinawa 905-2192 Japan
- 3Escuela de Ingeniería en Biotecnología, Centro de Biotecnología, Universidad Católica del Maule, Talca, Chile
Abstract
The microbial degradation of natural rubber (NR), which is mainly composed of cis-1,4-polyisoprene, is a promising sustainable strategy for rubber waste treatment. In rubber-degrading actinomycetes, the polymer is cleaved by the latex-clearing protein (Lcp) into oligo-isoprene aldehydes (OIA), which are then oxidized and channeled into the β-oxidation pathway. Some strains employ heterodimeric molybdenum hydroxylases (OxiAB) for this oxidation, whereas others, including Gordonia and Nocardia strains, lack oxiA/oxiB adjacent to lcp and instead use NAD(P)+-dependent aldehyde dehydrogenases (ALDHs); however, the ALDH repertoire differs among strains. Here, we identified the ALDHs responsible for OIA oxidation in Rhodococcus sp. RDE2. Cell-free extracts oxidized OIA preferentially with NAD+, although substantial NADP+-dependent activity (~37% of the NAD+-dependent activity) was also detected. Neither activity was induced during NR growth. Six candidate ALDHs were selected by combining homology searches, qRT-PCR, and heterologous expression analyses in Escherichia coli. Among the purified candidates, only LPH33_RS08240 and LPH33_RS17900 exhibited substantial NAD+-dependent OIA-oxidizing activity, which was 2.0- and 1.3-fold higher than that of the reference VH2 ALDH (GPOL_c02580), respectively. Deletion of either gene reduced both NR and OIA oxidation activities, identifying these two enzymes as major contributors to NAD+-dependent OIA oxidation in RDE2 and, to our knowledge, as the first OIA-oxidizing ALDHs identified in the genus Rhodococcus. Double knockouts did not abolish these activities, indicating contributions from additional ALDHs, consistent with the NADP+-dependent activities detected for the three other candidates. These findings extend the OIA-oxidizing ALDH repertoire of rubber-degrading actinomycetes and provide a foundation for engineering rubber-derived bioconversion.
Key points: LPH33_RS08240 and RS17900 are the first OIA-oxidizing ALDHs found in Rhodococcus.
Deleting both genes lowers rubber growth and OIA activity without abolishing either.
NADP+-linked ALDHs may couple rubber degradation to reductive biosynthesis in RDE2.
Supplementary Information: The online version contains supplementary material available at https://doi.org/10.1007/s00253-026-13993-w.
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BibTeX
@article{kawagiwa2026aldehyde,
title = {{Aldehyde dehydrogenases for oligo-isoprene aldehyde oxidation in Rhodococcus sp. RDE2}},
author = {Yukimura Kawagiwa and Namiko Gibu and Rodrigo Andler and Daisuke Kasai},
journal = {Applied Microbiology and Biotechnology},
year = {2026},
month = aug,
doi = {10.1007/s00253-026-13993-w},
url = {https://doi.org/10.1007/s00253-026-13993-w},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Aldehyde dehydrogenases for oligo-isoprene aldehyde oxidation in Rhodococcus sp. RDE2
AU - Yukimura Kawagiwa
AU - Namiko Gibu
AU - Rodrigo Andler
AU - Daisuke Kasai
PY - 2026
DA - 2026/08/08
JO - Applied Microbiology and Biotechnology
DO - 10.1007/s00253-026-13993-w
UR - https://doi.org/10.1007/s00253-026-13993-w
AB - The microbial degradation of natural rubber (NR), which is mainly composed of cis-1,4-polyisoprene, is a promising sustainable strategy for rubber waste treatment. In rubber-degrading actinomycetes, the polymer is cleaved by the latex-clearing protein (Lcp) into oligo-isoprene aldehydes (OIA), which are then oxidized and channeled into the β-oxidation pathway. Some strains employ heterodimeric molybdenum hydroxylases (OxiAB) for this oxidation, whereas others, including Gordonia and Nocardia strains, lack oxiA/oxiB adjacent to lcp and instead use NAD(P)+-dependent aldehyde dehydrogenases (ALDHs); however, the ALDH repertoire differs among strains. Here, we identified the ALDHs responsible for OIA oxidation in Rhodococcus sp. RDE2. Cell-free extracts oxidized OIA preferentially with NAD+, although substantial NADP+-dependent activity (~37% of the NAD+-dependent activity) was also detected. Neither activity was induced during NR growth. Six candidate ALDHs were selected by combining homology searches, qRT-PCR, and heterologous expression analyses in Escherichia coli. Among the purified candidates, only LPH33_RS08240 and LPH33_RS17900 exhibited substantial NAD+-dependent OIA-oxidizing activity, which was 2.0- and 1.3-fold higher than that of the reference VH2 ALDH (GPOL_c02580), respectively. Deletion of either gene reduced both NR and OIA oxidation activities, identifying these two enzymes as major contributors to NAD+-dependent OIA oxidation in RDE2 and, to our knowledge, as the first OIA-oxidizing ALDHs identified in the genus Rhodococcus. Double knockouts did not abolish these activities, indicating contributions from additional ALDHs, consistent with the NADP+-dependent activities detected for the three other candidates. These findings extend the OIA-oxidizing ALDH repertoire of rubber-degrading actinomycetes and provide a foundation for engineering rubber-derived bioconversion. Key points: LPH33_RS08240 and RS17900 are the first OIA-oxidizing ALDHs found in Rhodococcus. Deleting both genes lowers rubber growth and OIA activity without abolishing either. NADP+-linked ALDHs may couple rubber degradation to reductive biosynthesis in RDE2. Supplementary Information: The online version contains supplementary material available at https://doi.org/10.1007/s00253-026-13993-w.
SN - 0175-7598
SN - 1432-0614
ER -