A Baeyer-Villiger Monooxygenase Gene Involved in the Synthesis of Lysergic Acid Amides Affects the Interaction of the Fungus Metarhizium brunneum with Insects

Several fungi, including the plant root symbiont and insect pathogen Metarhizium brunneum, produce lysergic acid amides via a branch of the ergot alkaloid pathway. Lysergic acid amides include important pharmaceuticals and pharmaceutical lead compounds and have potential ecological significance, making knowledge of their biosynthesis relevant. Many steps in the biosynthesis of lysergic acid amides have been determined, but terminal steps in the synthesis of lysergic acid α-hydroxyethylamide (LAH)-by far the most abundant lysergic acid amide in M. brunneum-are unknown. Ergot alkaloid synthesis (eas) genes are clustered in the genomes of fungi that produce these compounds, and the eas clusters of LAH producers contain two uncharacterized genes (easO and easP) not found in fungi that do not produce LAH. Knockout of easO via a CRISPR-Cas9 approach eliminated LAH and resulted in accumulation of the alternate lysergic acid amides lysergyl-alanine and ergonovine. Despite the elimination of LAH, the total concentration of lysergic acid derivatives was not affected significantly by the mutation. Complementation with a wild-type allele of easO restored the ability to synthesize LAH. Substrate feeding studies indicated that neither lysergyl-alanine nor ergonovine were substrates for the product of easO (EasO). EasO had structural similarity to Baeyer-Villiger monooxygenases (BVMOs), and labeling studies with deuterated alanine supported a role for a BVMO in LAH biosynthesis. The easO knockout had reduced virulence to larvae of the insect Galleria mellonella, indicating that LAH contributes to virulence of M. brunneum on insects and that LAH has biological activities different from ergonovine and lysergyl-alanine. IMPORTANCE Fungi in the genus Metarhizium are important plant root symbionts and insect pathogens. They are formulated commercially to protect plants from insect pests. Several Metarhizium species, including M. brunneum, were recently shown to produce ergot alkaloids, a class of specialized metabolites studied extensively in other fungi because of their importance in agriculture and medicine. A biological role for ergot alkaloids in Metarhizium species had not been demonstrated previously. Moreover, the types of ergot alkaloids produced by Metarhizium species are lysergic acid amides, which have served directly or indirectly as important pharmaceutical compounds. The terminal steps in the synthesis of the most abundant lysergic acid amide in Metarhizium species and several other fungi (LAH) have not been determined. The results of this study demonstrate the role of a previously unstudied gene in LAH synthesis and indicate that LAH contributes to virulence of M. brunneum on insects.

Several Metarhizium Species Produce Ergot Alkaloids in a Condition-Specific Manner

Genomic sequence data indicate that certain fungi in the genus Metarhizium have the capacity to produce lysergic acid-derived ergot alkaloids, but accumulation of ergot alkaloids in these fungi has not been demonstrated previously. We assayed several Metarhizium species grown under different conditions for accumulation of ergot alkaloids. Isolates of M. brunneum and M. anisopliae accumulated the lysergic acid amides lysergic acid α-hydroxyethyl amide, ergine, and ergonovine on sucrose-yeast extract agar but not on two other tested media. Isolates of six other Metarhizium species did not accumulate ergot alkaloids on sucrose-yeast extract agar. Conidia of M. brunneum lacked detectable ergot alkaloids, and mycelia of this fungus secreted over 80% of their ergot alkaloid yield into the culture medium. Isolates of M. brunneum, M. flavoviride, M. robertsii, M. acridum, and M. anisopliae produced high concentrations of ergot alkaloids in infected larvae of the model insect Galleria mellonella, but larvae infected with M. pingshaense, M. album, M. majus, and M. guizhouense lacked detectable ergot alkaloids. Alkaloid concentrations were significantly higher when insects were alive (as opposed to killed by freezing or gas) at the time of inoculation with M. brunneum Roots of corn and beans were inoculated with M. brunneum or M. flavoviride and global metabolomic analyses indicated that the inoculated roots were colonized, though no ergot alkaloids were detected. The data demonstrate that several Metarhizium species produce ergot alkaloids of the lysergic acid amide class and that production of ergot alkaloids is tightly regulated and associated with insect colonization.IMPORTANCE Our discovery of ergot alkaloids in fungi of the genus Metarhizium has agricultural and pharmaceutical implications. Ergot alkaloids produced by other fungi in the family Clavicipitaceae accumulate in forage grasses or grain crops; in this context they are considered toxins, though their presence also may deter or kill insect pests. Our data report ergot alkaloids in Metarhizium species and indicate a close association of ergot alkaloid accumulation with insect colonization. The lack of accumulation of alkaloids in spores of the fungi and in plants colonized by the fungi affirms the safety of using Metarhizium species as biocontrol agents. Ergot alkaloids produced by other fungi have been exploited to produce powerful pharmaceuticals. The class of ergot alkaloids discovered in Metarhizium species (lysergic acid amides) and their secretion into the growth medium make Metarhizium species a potential platform for future studies on ergot alkaloid synthesis and modification.

Headache Characteristics and Clinical Features of Elderly Migraine Patients

OBJECTIVE

To investigate the headache characteristics and clinical features of elderly migraine patients at a tertiary headache center.

METHODS

We retrospectively reviewed 239 records of migraine patients, over the age of 64 at the first visit, who had migraine as defined by the International Classification of Headache Disorders 3rd edition (beta version) from 2006 to 2015 based on the Marseille registry at Timone Hospital.

RESULTS

13.8% (33/239) patients had migraine with aura only, 13.0% (31/239) had both diagnoses. Of the patients who presented with migraine with aura, 13.4% (32/239) presented with aura without headache. Unilateral pain location was reported by 58.6% (140/239) of patients and the throbbing type of pain was present in 50.2% (120/239) of our study group. Photo- and phonophobia were observed in 77.4% (185/239) and 79.5% (190/239) of patients. Seventy-nine out of 239 (30.1%) patients were found to have probable medication overuse. Within this group, 31.65% (25/79) overused triptan and 70.9% (56/79) overused combination analgesics. We found higher frequencies of migraine for patients whose age at onset of migraine was younger than 18 years, and low frequency migraine was reported more frequently in the later onset group (P = .0357).

DISCUSSION

We assess the headache characteristics of elderly migraine patients who were seen at our tertiary headache center and report the high frequency of probable medication overuse headache in this study group. Finally, we suggest that age of onset is an important factor in the clinical profile of these patients.

Ergotamine Use and Overuse in Taiwan: A Retrospective Cohort Study

OBJECTIVE

The aim of this study was to investigate the pattern of ergotamine prescription and overuse in Taiwan.

BACKGROUND

Ergotamine is a frequently prescribed medication for the treatment of migraine, although excessive use may lead to medication-overuse headache.

METHODS

We conducted a retrospective cohort study by using the Longitudinal Health Insurance Database 2005 in Taiwan. Patients enrolled in the study were between the ages of 18 and 80 years, received at least two prescriptions of ergotamine, and follow-up for more than 1 year at outpatient clinics during 1999 to 2013. Each ergotamine prescription was converted into a defined daily dose (DDD) and patients were sorted into two groups: occasional users, having fewer than 3 consecutive months of use, and regular users, with 3 consecutive months of use or more. Regular users were further divided into overusers (DDDs ≥ 10 per month) and non-overusers.

RESULTS

A total of 41,023 migraine patients were enrolled in the study; 5803 patients were classified as regular users, with 859 of those being overusers. Of the ergotamine overusers, around 698/859 (82%) continued to use, and 443/859 (52%) remained overusers of ergotamine in the subsequent year after the index date. The most frequently prescribed prophylactic medications were propranolol and flunarizine, which were prescribed in 30.4% and 20.0% of overuse patients, respectively.

CONCLUSIONS

Ergotamine overuse remains common in Taiwan, while prophylactic medicine is still underutilized. More education on ergotamine-overuse headache is needed to improve awareness.