Using a global account to deposit transaction fee for multitenant system

I am building a system on top of blockcerts that would allow various issuers to issue certificates. Behind the scene, the system would generate addresses etc for each issuer.

However, while submitting the transaction, I would like to use a global account to deposit transaction fee so each issuer does not have to worry about filling their wallet.

One solution I can think of is that before the system issue the certificate on behalf of the issuer, it can transfer necessary funds from global account to issuer account and then issue. However, it seems unnecessary exchange of funds.