Convert list of dicts to string

I'm very new to Python, so forgive me if this is easier than it seems to me.

I'm being presented with a list of dicts as follows:

[{'directMember': 'true', 'memberType': 'User', 'memberId': 'address1@example.com'},  
 {'directMember': 'true', 'memberType': 'User', 'memberId': 'address2@example.com'},  
 {'directMember': 'true', 'memberType': 'User', 'memberId': 'address3@example.com'}]

I would like to generate a simple string of memberIds, such as

address1@example.com , address2@example.com , address3@example.com

но каждый метод преобразования списка в строку, который я пробовал, терпит неудачу, потому что задействованы dicts.

Есть какой-нибудь совет?