Strain-dependent response to Cu 2+ in the expression of laccase in Pycnoporus coccineus
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ORIGINAL PAPER
Strain‑dependent response to Cu2+ in the expression of laccase in Pycnoporus coccineus Ju‑Wan Park · Hyeon‑Woo Kang · Byung‑Suk Ha · Sin‑Il Kim · Soonok Kim · Hyeon‑Su Ro
Received: 21 September 2014 / Revised: 30 January 2015 / Accepted: 5 February 2015 © Springer-Verlag Berlin Heidelberg 2015
Abstract The effects of Cu2+ on the activity and expression of laccase were investigated in seven different strains of Pycnoporus coccineus collected from different regions in Korea. Cu2+ was toxic to mycelial growth at concentrations greater than 0.5 mM CuSO4 and showed complete growth inhibition at 1 mM in the liquid culture. However, Cu2+ significantly upregulated the extracellular laccase activity at 0.2 mM in five strains of P. coccineus, IUM4209, IUM0032, IUM0450, IUM0470, and IUM4093, whereas two strains, IUM0253 and IUM0049, did not respond to Cu2+, despite being closely related to the other five strains. Subsequent RT-PCR analysis also showed that the laccase mRNA was highly expressed only in the former five strains in the presence of Cu2+. Taken together, these results indicate that Cu2+ regulates expression of the laccase gene in a strain-dependent manner. The five strains commonly produced a single predominant laccase protein with a molecular weight of 68 kDa. Peptide sequencing revealed that the laccase was a homolog of Lcc1 of P. coccineus, which was isolated in China. The Cu2+-induced culture supernatants exhibited high degradation of polycyclic aromatic hydrocarbons, indicating that the 68-kDa laccase is the primary extracellular degradative enzyme in P. coccineus. Keywords Cu2+ · Laccase · PAH · Pycnoporus Communicated by Olaf Kniemeyer. J.‑W. Park · H.‑W. Kang · B.‑S. Ha · S.‑I. Kim · H.‑S. Ro (*) Division of Applied Life Science and Research Institute for Life Science, Gyeongsang National University, Jinju 660‑701, Korea e-mail: [email protected] S. Kim National Institute of Biological Resources, Incheon 404‑708, Korea
Introduction Mushrooms are a group of fungi, that occasionally form fruiting bodies that produce sexual spores for reproduction. Mushrooms are widely distributed in nature and play critical roles in the recycling of organic matter, particularly wood materials. Mushroom enzymes, including laccase, lignin peroxidase (LiP), and Mn peroxidase (MnP), are the major enzymes that degrade polyphenolic lignin components of plant cell walls (Barr and Aust 1994). Mushrooms also remove recalcitrant aromatic pollutants, including polycyclic aromatic hydrocarbons (PAHs) (Cerniglia 1992; Punnapayak et al. 2009), textile dyes (Dos Santos et al. 2004), 2,4,6-trinitrotoluene (TNT) (Van Aken and Agathos 2002), and endocrine-disrupting compounds (Sato et al. 2002; Soares et al. 2005). Pycnoporus mushrooms belong to the Polyporaceae family and consist of four species, P. cinnabarinus, P. coccineus, P. puniceus, and P. sanguineus. Pycnoporus commonly produce red phenoxazinone pigments, such as cinnabarinic acid and cinnabarin (Sullivan and Henry 1971), via laccase activity using 3-hydroxyanth
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